A Finnish study involving 338 older adults (average age 66) has found that greater muscle strength is associated with better cognitive function.

Muscle strength was measured utilising handgrip strength, three lower body exercises such as leg extension, leg flexion and leg press and two upper body exercises such as chest press and seated row.

Handgrip strength, easy to measure, has been widely used as a measure of muscle strength, and has been associated with dementia risk among the very old. However, in this study, handgrip strength on its own showed no association with cognitive function. But both upper body strength and lower body strength were independently associated with cognitive function.

It may be that handgrip strength is only useful for older, more cognitively impaired adults.

These are gender-specific associations — muscle strength was significantly greater in men, but there was no difference in cognitive performance between men and women.

The finding is supported by previous research that found a link between walking speed and cognition in older adults, and by a 2015 study that found a striking correlation between leg power and cognition.

This 10-year British study involved 324 older female twins (average age 55). Both the degree of cognitive decline over the ten year period, and the amount of gray matter, was significantly correlated with high muscle fitness (measured by leg extension muscle power). The correlation was greater than for any other lifestyle factor tested

A new MRI technique has revealed that it is the structural integrity of the hippocampus more than its size that reflects fitness and correlates with cognitive performance.

Research has focused on hippocampal size because it is easier to measure, and in children and older adults there are strong correlations between hippocampal size and memory. But this is less true for healthy, young adults. This new, subtler, technique reveals that something else is going on — something that has probably been masked by the effects of size in older adults (whose hippocampi are shrinking) and younger children (whose brains are still growing).

The technique measures viscoelasticity. If the hippocampus is more elastic, memory is better. When it’s more viscous, memory is worse. Those with better aerobic fitness had better hippocampal elasticity.

A review of 39 studies investigating the effect of exercise on cognition in older adults (50+) confirms that physical exercise does indeed improve cognitive function in the over 50s, regardless of their cognitive status. Aerobic exercise, resistance training, multicomponent training and tai chi, all had significant effects. However, exercise sessions needed to be at least 45 minutes and moderate intensity. Because aerobic exercise and resistance training had different effects (aerobic exercise helped overall cognition, while resistance training was particularly beneficial for executive function and working memory), it’s recommended that an exercise program include both.

These positive changes have been demonstrated to occur with very low to very high exercise intensities, with effects lasting for up to two hours after the end of the exercise bout.

While brainwaves are all enhanced across the brain, hippocampal theta brainwaves are particularly enhanced by exercise, and the effects of this suggest that exercise particularly helps with tasks that depend on hippocampal-prefrontal interactions. Exercise also helps increase blood flow to the frontal regions.

One of the most dramatic effects of exercise is on neurochemical levels, including neurotransmitters and growth factors (such as BDNF).

A study involving 35 adults with MCI found that those who exercised four times a week over a six-month period increased their volume of gray matter. But those who participated in aerobic exercise experienced significantly greater gains than those who just stretched, who also showed signs of white matter loss.

A study involving 18 volunteers who performed a simple orientation discrimination while on a stationary bicycle, has found that low-intensity exercise boosted activation in the visual cortex, compared with activation levels when at rest or during high-intensity exercise.

The changes suggest that the neurons in the visual cortex were most sensitive to the orientation stimuli during the low-intensity exercise condition relative to the other conditions. It’s suggested that this reflects an evolutionary pressure for the visual system to be more sensitive when the individual is actively exploring the environment (as opposed to, say, running away).

Chemo-brain common among women with breast cancer

A study involving 581 breast cancer patients and 364 healthy age-matched people (mean age 53) has found that women with breast cancer reported significantly greater cognitive difficulties for up to six months after chemotherapy. Cognitive difficulties were evaluated using FACT-Cog, an assessment that examines a person's own perceived impairment as well as cognitive impairment perceived by others.

Compared to healthy controls, the FACT-Cog scores of women with breast cancer were 45% lower at outset. This difference increased substantially after chemotherapy (see graph). The first assessment after chemotherapy was at 4.8 months, with the second 6 months after that (i.e, nearly a year after chemotherapy). Patients were also much more likely to report significant cognitive decline from diagnosis to the first post-chemotherapy assessment (45.2% vs 10.4% of the controls), and from prechemotherapy to second post-chemotherapy assessment (36.5% v 13.6%).

Having more anxiety and depressive symptoms at the outset, and having lower cognitive reserve (assessed by a reading score), were significantly associated with lower scores.

Those who received hormone therapy and/or radiation treatment after chemotherapy had similar cognitive problems to women who received chemotherapy alone.

A rat study suggests one reason for chemo-brain is an effect of chemotherapy on the neurotransmitters dopamine and serotonin. Both of these are important for both mood and cognition.

After giving carboplatin (commonly used with breast, bladder, colon and other cancers) to rats over four weeks, researchers found that the release and uptake of both dopamine and serotonin in their brains became impaired, although overall levels didn’t change. The rats also showed impaired cognition.

Exercise helps memory for breast cancer survivors

A role for dopamine and serotonin in chemo-brain is consistent with findings that anxiety and depression are risk factors for chemo-brain. No surprise then, that a study has found that physical exercise helps improve cognition in breast cancer survivors.

The study used self-reported data from 1,477 breast cancer survivors, as well as from accelerometers worn by 362 of the women. It found that breast cancer survivors who did more moderate or vigorous physical activity (including brisk walking, biking, jogging, or an exercise class) had fewer subjective memory problems.

Higher levels of physical activity were associated with lower levels of fatigue and distress, and higher levels of physical confidence. The researchers suggest that exercise reduces subjective memory problems via these factors.

Cognitive-behavioral therapy may help

A cognitive-behavioral therapy called "Memory and Attention Adaptation Training" (MAAT), which helps cancer survivors to increase their awareness of situations where memory problems can arise and to develop skills to either prevent memory failure or to compensate for memory dysfunction, has been trialed in a small randomized study involving 47 Caucasian breast cancer survivors. The patients were an average of four years post-chemotherapy.

The participants were either assigned to eight visits of MAAT (30 to 45 minutes each visit) or supportive talk therapy for the same length of time. Both treatments were delivered over a videoconference network between health centers.

MAAT participants reported significantly fewer memory problems as well as improved processing speed two months after treatment. They also reported much less anxiety about cognitive problems.

Data from 876 patients (average age 78) in the 30-year Cardiovascular Health Study show that virtually any type of aerobic physical activity can improve brain volume and reduce Alzheimer's risk.

A higher level of physical activity was associated with larger brain volumes in the frontal, temporal, and parietal lobes including the hippocampus, thalamus and basal ganglia. Among those with MCI or Alzheimer's (25% of the participants), higher levels of physical activity were also associated with less brain atrophy. An increase in physical activity was also associated with larger grey matter volumes in the left inferior orbitofrontal cortex and the left precuneus.

Further analysis of 326 of the participants found that those with the highest energy expenditure were half as likely to have developed Alzheimer's disease five years later.

The study does not look at whether some types of physical activity are better than others, unfortunately, but its message that overall physical activity, regardless of type, helps in the fight against cognitive impairment is encouraging.

A small study that fitted 29 young adults (18-31) and 31 older adults (55-82) with a device that recorded steps taken and the vigor and speed with which they were made, has found that those older adults with a higher step rate performed better on memory tasks than those who were more sedentary. There was no such effect seen among the younger adults.

Improved memory was found for both visual and episodic memory, and was strongest with the episodic memory task. This required recalling which name went with a person's face — an everyday task that older adults often have difficulty with.

However, the effect on visual memory had more to do with time spent sedentary than step rate. With the face-name task, both time spent sedentary and step rate were significant factors, and both factors had a greater effect than they had on visual memory.

Depression and hypertension were both adjusted for in the analysis.

There was no significant difference in executive function related to physical activity, although previous studies have found an effect. Less surprisingly, there was also no significant effect on verbal memory.

Both findings might be explained in terms of cognitive demand. The evidence suggests that the effect of physical exercise is only seen when the task is sufficiently cognitively demanding. No surprise that verbal memory (which tends to be much less affected by age) didn't meet that challenge, but interestingly, the older adults in this study were also less impaired on executive function than on visual memory. This is unusual, and reminds us that, especially with small studies, you cannot ignore the individual differences.

This general principle may also account for the lack of effect among younger adults. It is interesting to speculate whether physical activity effects would be found if the younger adults were given much more challenging tasks (either by increasing their difficulty, or selecting a group who were less capable).

Step Rate was calculated by total steps taken divided by the total minutes in light, moderate, and vigorous activities, based on the notion that this would provide an independent indicator of physical activity intensity (how briskly one is walking). Sedentary Time was the total minutes spent sedentary.

A two-year study which involved metabolic testing of 50 people, suggests that Alzheimer's disease consists of three distinct subtypes, each one of which may need to be treated differently. The finding may help explain why it has been so hard to find effective treatments for the disease.

The subtypes are:

Inflammatory, in which markers such as C-reactive protein and serum albumin to globulin ratios are increased.

Non-inflammatory, in which these markers are not increased but other metabolic abnormalities (such as insulin resistance, hypovitaminosis D, and hyper-homocysteinemia) are present. This tends to affect slightly older individuals than the first subtype: 80s rather than 70s.

Cortical, which affects relatively young individuals (typically 50s- early 70s) and appears more widely distributed across the brain than the other subtypes, showing widespread cortical atrophy rather than marked hippocampal atrophy. It typically presents with language and number difficulties first, rather than memory loss. Typically, there is an impaired ability to hold onto a train of thought. It is often misdiagnosed, typically affects people without a family history of Alzheimer's, who do not have an Alzheimer's-related gene, and is associated with a significant zinc deficiency (Zinc is implicated in multiple Alzheimer's-related metabolic processes, such as insulin resistance, chronic inflammation, ADAM10 proteolytic activity, and hormonal signaling. Zinc deficiency is relatively common, and associated with increasing age.).

The cortical subtype appears to be fundamentally a different condition than the other two.

I note a study I reported on last year, that found different molecular structures of amyloid-beta fibrils in the brains of Alzheimer's patients with different clinical histories and degrees of brain damage. That was a very small study, indicative only. However, I do wonder if there's any connection between these two findings. At the least, I think this approach a promising one.

It's also worth noting that the present study built on an earlier study, which showed that a program of lifestyle, exercise and diet changes designed to improve the body's metabolism reversed cognitive decline within 3-6 months in nine out of 10 patients with early Alzheimer's disease or its precursors. Note that this was a very small pilot program, and needs a proper clinical trial. Nevertheless, it is certainly very interesting.

A study involving 845 secondary school students has revealed that each hour per day spent watching TV, using the internet or playing computer games at average age 14.5 years was associated with poorer GCSE grades at age 16. Additionally, each hour of daily homework and reading was linked to significantly better grades. Surprisingly, however, the amount of physical activity had no effect on academic performance.

Median screen time was four hours a day, of which around half was spent watching TV; median sedentary non-screen time (reading/homework) was 1.5 hours.

Each hour per day of time spent in front of the TV or computer in Year 10 was associated with 9.3 fewer GCSE points in Year 11 — the equivalent to two grades in one subject or one grade in each of two subjects. Two hours was therefore associated with 18 fewer points at GCSE, and the median of four hours, with a worrying 36 fewer points.

The burning question: are some screens better than others? Comparison of the different screen activities revealed that TV viewing was the most detrimental to grades.

More positively, each hour of daily homework and reading was associated with an average 23.1 more GCSE points. This was a U-shaped function, however, with pupils doing over four hours of reading or homework a day performing less well than their peers. But the number of pupils in this category was relatively low (only 52 pupils) and may include students who were struggling at school.

The benefits from spending time on homework or reading were not simply a consequence of spending less time staring at a screen; screen time and time spent reading or doing homework were independently associated with academic performance.

Do note that, although some homework was doubtless done on the computer, this was not counted as screen time for the purposes of this study.

The finding of no significant association between moderate to vigorous physical activity and academic performance is more surprising, given the evidence for the benefits of exercise and physical fitness for cognition. The median was 39 minutes of moderate to vigorous physical activity a day, with a quarter of the students getting less than 20 minutes a day, and a quarter getting more than 65 minutes.

The data used was from the ROOTS study, a large longitudinal study assessing health and wellbeing during adolescence. Objective levels of activity and time spent sitting were assessed through a combination of heart rate and movement sensing. Screen time, time spent doing homework, and reading for pleasure, relied on self-report. Medians were used rather than means, because of the degree of skew in the data.

A study involving 100 healthy older adults (aged 60-80) has found that those with higher levels of physical activity showed more variable spontaneous brain activity in certain brain regions (including the precuneus, hippocampus, medial and lateral prefrontal, and temporal cortices). Moreover, this relationship was positively associated with better white-matter structure.

Higher rates of activity when the brain is “at rest” have previously been shown to be associated with better cognitive performance in older adults, especially in IQ and memory.

The brain regions showing this relationship all play an important role in major resting-state networks, including the default mode network, the motor network, and networks associated with executive control and salience detection. They are all highly connected.

Participants' physical activity over a week was measured using accelerometers. Cardiorespiratory fitness was also assessed. Participants were generally not very active and not very fit.

The findings add to evidence linking higher fitness and physical activity with greater brain integrity and higher cognitive performance. They are also consistent with previous studies showing an increase in such brain signal fluctuations among older adults participating in physical exercise programs.

Interestingly, level of brain activity fluctuations was only correlated with physical activity, not with cardiorespiratory fitness. This indicates that CRF and physical exercise cannot be considered as functional equivalents — there must be some aspects of physical activity not captured by a measure of cardiorespiratory fitness.

It's also worth noting that there wasn't a significant correlation between sedentary time and resting-state brain activity fluctuations, although this may be because the participants all showed not-very-dissimilar levels of sedentary time.

The study involved 1,635 older adults (70-89) who were enrolled in the Lifestyle Interventions and Independence for Elders (LIFE) study. They were sedentary adults who were at risk for mobility disability but able to walk about a quarter mile. Participants had no significant cognitive impairment (as measured by the MMSE) at the beginning of the study. Around 90% (1476) made it to the end of the study, and were included in the analysis.

Half the participants were randomly assigned to a structured, moderate-intensity physical activity program that included walking, resistance training, and flexibility exercises, and the other half to a health education program of educational workshops and upper-extremity stretching.

In the physical activity condition, participants were expected to attend 2 center-based visits per week and perform home-based activity 3 to 4 times per week. The sessions progressed toward a goal of 30 minutes of walking at moderate intensity, 10 minutes of primarily lower-extremity strength training with ankle weights, and 10 minutes of balance training and large muscle group flexibility exercises.

The health education group attended weekly health education workshops during the first 26 weeks of the intervention and at least monthly sessions thereafter. Sessions lasted 60 to 90 minutes and consisted of interactive and didactic presentations, facilitator demonstrations, guest speakers, or field trips. Sessions included approximately 10 minutes of group discussion and interaction and 5 to 10 minutes of upper-extremity stretching and flexibility exercises.

Cognitive assessments were made at the beginning of the study and at 24 months, as well as a computerized assessment at either 18 or 30 months.

At the end of the study, there was no significant difference in cognitive score, or incidence of MCI or dementia, between the two groups. However, those in the exercise group who were 80 years or older ( 307) and those with poorer baseline physical performance ( 328) did show significantly better performance in executive function.

Executive function is not only a critical function in retaining the ability to live independently, research has also shown that it is the most sensitive cognitive domain to physical exercise.

Note also that there was no absolute control group — that is, people who received no intervention. Both groups showed remarkably stable cognitive scores over the two years, suggesting that both interventions were in fact effective in “holding the line”.

While this finding is disappointing and a little surprising, it is not entirely inconsistent with the research. Studies into the benefits of physical exercise for fighting age-related cognitive decline and dementia have produced mixed results. It does seem clear that the relationship is not a simple one, and what's needed is a better understanding of the complexities of the relationship. For example, elements of exercise that are critical, and the types of people (genes; health; previous social, physical, and cognitive attributes) that may benefit.

A six-month pilot study involving 101 healthy older adults (65+), who were randomly put into one of three exercise interventions or a no-change control, has found that the exercise groups all showed significant improvement in visual-spatial processing and attention, with more improvement in visual-spatial processing occurring in those with higher levels of exercise.

The benefits of increasing exercise for visual-spatial processing, however, were fully accounted for by improvements in cardiorespiratory fitness, suggesting that exercise intensity may be more important than exercise duration.

The researchers suggest that individualized exercise programs designed to maximize cardiorespiratory fitness will be of greatest benefit.

The three exercise levels were: 150 minutes per week (the recommended level); 75 minutes per week; 225 minutes per week. Exercise was supervised, and mainly consisted of treadmill walking of moderate intensity. Participants exercised 3-5 days a week. Performance in five cognitive domains were tested: Verbal Memory, Visuospatial Processing, Simple Attention, Set Maintenance and Shifting, and Reasoning.

Note that only 77 individuals made it through the trial, and also adhered to at least 80% of the alloted amount of exercise. Unsurprisingly, the 225-minute group had the most trouble meeting the allotment: 70% of the group managed it, compared to 82% of the 75-minute group, and 85% of the 150-minute group. It's worth noting that, of those who met the 80% requirement, almost all (>95%) fully adhered to the prescription, and this was true across all exercise prescriptions.

A six-week study involving 619 cancer patients has found that those who took part in a simple home-based exercise program significantly reduced their cognitive impairment ('chemo-brain'). The EXCAP (Exercise for Cancer Patients) was developed by the researchers some years ago, and this evaluation was a phase III randomized study for early-stage chemotherapy patients. Half the group were given standard care (no exercise during chemotherapy), while the others were given instruction to walk daily and carry out low-to-moderate resistance band training for 10 minutes, 5 days a week.

This very modest increase in exercise (the 'no-exercise' group walked on average 3,800 steps a day, while the excap group walked on average 5,000 steps) had significant effects:

lower levels of inflammation

less brain 'fogginess'

fewer memory problems

greater mobility.

Exercisers who received chemotherapy in 2-week cycles reported the greatest benefits, compared to other timing cycles.

A review and a large study have recently added to the growing evidence that type 2 diabetes is not only a risk factor for Alzheimer's, but is also linked to poorer cognitive function and faster age-related cognitive decline. The amount of this also seems to be related to glucose control in a dose-dependent manner.

Somewhat surprisingly, there is evidence that the association is not linked to vascular factors, but is in significant part explained by neuron loss. That part is not surprising — brains 'naturally' shrink with age, and growing evidence points to the importance of exercise (which promotes the growth of new neurons) in combating that loss. If diabetics are less likely to exercise (which seems likely, given the strong association with obesity), this may, at least in part, account for the greater brain atrophy.

Type 2 diabetes linked to poorer executive function

A meta-analysis of 60 studies involving a total of 9815 people with Type 2 diabetes and 69,254 control individuals, has found a small but reliable association between diabetes and poorer executive function. This was true across all aspects of executive function tested: verbal fluency, mental flexibility, inhibition, working memory, and attention.

Unfortunately, effective diabetes management does depend quite heavily on executive function, making this something of a negative feedback cycle.

Diabetes in midlife linked to greater age-related cognitive decline

A long-running U.S. study involving 13,351 adults, has found that cognitive decline over 19 years was 19% greater among those who had diabetes in midlife. Moreover, cognitive decline increased with higher hemoglobin A1c level and longer duration of diabetes.

At the beginning of the study, participants were aged 48-67 (median: 57), and 13% of participants were diagnosed as diabetic. Cognition was tested using delayed word recall, digit symbol substitution, and word fluency tests.

The findings support the view that glucose control in midlife is important to protect against cognitive decline later in life.

Brain atrophy linked with cognitive decline in diabetes

A 2013 study showed that almost half of the cognitive impairment seen among diabetics was explained by their loss of gray matter.

Brain scans and cognitive tests of 350 people with Type 2 diabetes and 363 people without diabetes revealed that those with diabetes had more cerebral infarcts and greater shrinkage in specific regions of the brain. Diabetes was associated with poorer visuospatial memory, planning, visual memory, and processing speed. These associations were independent of vascular risk factors, cerebrovascular lesions, or white matter volume, but almost half of the associations were explained by the shrinkage of gray matter in the hippocampus and across the brain.

A study comparing 33 young adults (age 18-31) and 27 older adults (age 55-82) has found that older adults with higher cardiorespiratory (i.e., fitness) levels performed as well as young adults on executive function tests. On long-term memory tests (a face–name memory task, and a visual episodic memory task), young adults performed better than older fit adults, who in turn performed better than less fit older adults.

Fitness had no effect on young adults' memory or executive functions (although bearing in mind other research, I'd suggest that this may be due to the cognitive testing being insufficiently demanding).

The finding confirms earlier research linking cardiorespiratory fitness with better executive function in older adults, and extends the association to episodic memory.

A German study involving 40 healthy but initially sedentary older adults (aged 60-77) has found that those assigned to an exercise group (regular exercise on a treadmill for 3 months) improved not only their physical fitness but also their visual memory. This memory improvement was accompanied by increased blood flow and increased volume in the hippocampus. This improvement was seen in 7 of the 9 exercisers who were no older than 70. However, it tended not to be seen in those older than 70.

The control group (who also showed no such improvement) engaged in muscle relaxation sessions.

Increased brain perfusion as a result of physical exercise has previously been shown in younger people. This finding shows that some older adults may retain this ability, and also links this increase in blood flow to improvements in memory performance. It is less exciting to see that the effect was limited to visual short-term memory, but perhaps further exercise might have more far-reaching effects.

Cardiorespiratory fitness governs cerebrovascular health, not age

Another study has found that, among a group of older adults aged 55-85, blood flow in the gray matter was positively correlated with cardiorespiratory fitness and negatively correlated with age. That is, better cardiorespiratory fitness was linked to better blood flow in the brain, and both tended to decline with increasing age. Moreover, blood flow in the gray matter was entirely governed by cardiorespiratory fitness.

In other words, cerebrovascular health is largely a matter of your cardiorespiratory fitness, not your age.

A brain imaging study involving 24 9- and 10-year-olds has found that physical fitness was associated with significant differences in the integrity of several white-matter tracts in the brain: the corpus callosum, the superior longitudinal fasciculus, and the superior corona radiata. All of these are involved in learning and memory. The differences are associated with faster and more efficient nerve activity.

The findings build on previous research linking higher levels of aerobic fitness with greater volumes of gray matter (i.e., more neurons) in regions important for memory and learning, and suggest that better communication along the white-matter tracts might be another mechanism explaining why aerobic fitness is associated with improved cognition.

Factors such as socio-economic status, the timing of puberty, IQ, or a diagnosis of ADHD or other learning disabilities, were taken into account in the analysis.

Physical fitness linked to better reading skills in children

A study looking at brain activity during reading has found that physically fit children have faster and more robust brain responses during reading than their less-fit peers. These differences correspond with better language skills.

Brainwave patterns called "event-related potentials" (ERPs) vary by person, stimulus and task. A brainwave component called N400 is stronger when a sentence doesn't make sense compared to a meaningful sentence, for example. The component P600 is associated with grammatical rules.

The study found that children who were more fit (as measured by oxygen uptake during exercise) had higher amplitude N400 and P600 waves than their less-fit peers when reading normal or nonsensical sentences. The N400 also had shorter latency in children who were more fit, suggesting that they processed the same information more quickly. These differences corresponded to better reading performance and language comprehension.

Such findings suggest that higher fitness may be associated with a richer network of words and their meanings, and a greater ability to detect and/or repair syntactic errors.

Large study links physical fitness to school grades

A large Spanish study involving 2,038 young people (6-18; average age 10) has found that physical fitness was associated with better academic performance.

Fitness was measured in terms of cardiorespiratory capacity, motor ability and muscle strength. Cardiorespiratory capacity and motor ability were independently associated with all measures of academic performance (math grade, language grade, average of math and language grades, and overall grade point average), even after adjusting for fitness and fatness. Muscle strength was not associated with academic performance independent of cardiorespiratory capacity and motor ability.

Aerobic fitness boosts learning in school children

A study involving 48 9- and 10-year-olds has found that those with higher levels of physical fitness performed significantly better at a memorization task. The task involved memorizing names and locations on a fictitious map, either by study only or by being tested on the material as they studied. They were then tested a day later, under conditions of free recall and cued recall. Half the children were in the top 30% of their age group on a test measuring aerobic fitness, while the other half scored in the lowest 30%.

While there was no difference between the high-fitness and low-fitness groups at the initial learning session, and no difference on the delayed test when learning had involved study plus testing, the high-fitness group scored considerably better than the low-fitness group when learning involved study only (an average of 43% correct vs 25.8%).

This suggests that the benefits of fitness are greatest when initial learning is most challenging (as discussed at length by me in my book on practice, and in other articles, retrieval practice as a part of study improves learning significantly).

Childhood obesity linked to poorer cognitive control

A study involving 74 preadolescent children, of whom half were obese and half at a healthy weight, has found that the obese children were considerably slower at a task in which they were shown three fish facing either left or right and had to press a button based on the direction of the middle fish.

The healthy-weight children also improved their performance more after making an error, and their brain activity showed a larger response when they made an error. This difference was even greater in more demanding situations (the flanking fish could either point in the same direction or in the opposite direction). This suggests that childhood obesity is associated with poorer action monitoring, a vital aspect of cognitive control.

A new review from The Cochrane Library, based on six trials involving 289 people, has concluded that exercise can improve cognition and the ability of older people with dementia to carry out daily activities, such as walking short distances or getting up from a chair. However, there was no clear effect of exercise on depression in older people with dementia, and the reviewers say that more evidence is needed to understand how exercise could reduce the burden on family caregivers and health systems.

There are five healthy behaviors that appear to significantly reduce the risk of dementia,

A 35-year study that monitored the healthy behaviors of 2,235 Welsh men aged 45 to 59 at the beginning of the study has found that those who consistently followed at least four of these five healthy behaviors — regular exercise, no smoking, acceptable BMI, high fruit and vegetable intake, and low/moderate alcohol intake — experienced a 60% reduction in dementia and cognitive decline compared with people who followed none. They also had 70% fewer instances of diabetes, heart disease, and stroke,.

Exercise was the most important of these factors.

Only 5% of the men were living a healthy lifestyle (i.e., following at least 4 of these healthy behaviors). Just under half of the 2235 men were non-smokers (46%), and around a third (35%) had an acceptable BMI. Only 15 men ate their “5+” daily (!!), so the requirement was reduced to only three or more portions of fruit and vegetables, enabling 18% to reach it. 39% exercised regularly and 59% reported alcohol intake within the guidelines. Only two men managed five healthy behaviors, and 109 managed four; 19% managed three; 36% two; 31% one; 8% couldn’t manage any.

A pilot study involving 17 older adults with mild cognitive impairment and 18 controls (aged 60-88; average age 78) has found that a 12-week exercise program significantly improved performance on a semantic memory task, and also significantly improved brain efficiency, for both groups.

The program involved treadmill walking at a moderate intensity. The semantic memory tasks involved correctly recognizing names of celebrities well known to adults born in the 1930s and 40s (difficulty in remembering familiar names is one of the first tasks affected in Alzheimer’s), and recalling words presented in a list. Brain efficiency was demonstrated by a decrease in the activation intensity in the 11 brain regions involved in the memory task. The brain regions with improved efficiency corresponded to those involved in Alzheimer's disease, including the precuneus region, the temporal lobe, and the parahippocampalgyrus.

Participants also improved their cardiovascular fitness, by about 10%.

Data from 1.1 million young Swedish men (conscription information taken at age 18) has shown that those with poorer cardiovascular fitness were 2.5 times more likely to develop early-onset dementia later in life and 3.5 times more likely to develop mild cognitive impairment, while those with a lower IQ had a 4 times greater risk of early dementia and a threefold greater risk of MCI. A combination of both poor cardiovascular fitness and low IQ entailed a more than 7 times greater risk of early-onset dementia, and more than 8 times greater risk of MCI.

The increased risk remained even when controlled for other risk factors, such as heredity, medical history, and social-economic circumstances.

The development of early-onset dementia was taken from national disease registries. During the study period, a total of 660 men were diagnosed with early-onset dementia.

A further study of this database, taken from 488,484 men, of whom 487 developed early-onset dementia (at a median age of 54), found nine risk factors for early-onset dementia that together accounted for 68% of the attributable risk. These factors were alcohol intoxication, stroke, use of antipsychotics, depression, father's dementia, drug intoxication other than alcohol, low cognitive function at age 18, low stature at age 18, and high blood pressure at age 18.

A study involving 97 healthy older adults (65-89) has found that those with the “Alzheimer’s gene” (APOe4) who didn’t engage in much physical activity showed a decrease in hippocampal volume (3%) over 18 months. Those with the gene who did exercise showed no change in the size of their hippocampus, nor did those without the gene, regardless of exercise. Physical activity was classified as low if the participant reported two or fewer days per week of low intensity activity, such as no activity, slow walking or light chores. Physical activity was classified as high if the participant reported three or more days/week of moderate to vigorous activity

The finding suggests that those with the risky gene will benefit most from regular exercise — indeed, this is as yet the only known means to counteract hippocampal shrinkage.

Brain scans have revealed that those who regularly practiced yoga had larger brain volume in the somatosensory cortex (maps the body), superior parietal cortex (involved in directing attention), visual cortex (perhaps because of visualization techniques), hippocampus, precuneus and the posterior cingulate cortex (the last two involved in our concept of self).

As many of you will know, I like nature-improves-mind stories. A new twist comes from a small Scottish study, in which participants were fitted up with a mobile EEG monitor that enabled their brainwaves to be recorded as they walked for 25 minutes through one of three different urban settings: an urban shopping street, a path through green space, or a street in a busy commercial district. The monitors measured five ‘channels’ that are claimed to reflect “short-term excitement,” “frustration,” “engagement,” “arousal,” and “meditation level."

Consistent with Attention restoration theory, walkers entering the green zone showed lower frustration, engagement and arousal, and higher meditation, and then showed higher engagement when moving out of it — suggesting that their time in a natural environment had ‘refreshed’ their brain.

Data from the very large, long-running UK National Child Development Study has revealed that those who exercised at least four times weekly as both a child and an adult performed better on cognitive tests at age 50 than those who exercised two to three times per month or less, and the latter in turn performed better than those who hadn’t regularly exercised at all.

The data was collected through face-to-face interviews of more than 9,000 people at the ages of 11, 16, 33, 42, 46, and 50. Cognitive score was based on an immediate and delayed recall task (ten unrelated words), ability to name as many animals as possible in one minute, and time taken to cross out specified letters in a series.

The findings add a further perspective to the pile of evidence for the value of regular exercise in fighting age-related cognitive decline.

Previous research has pointed to an association between not having teeth and a higher risk of cognitive decline and dementia. One reason might have to do with inflammation — inflammation is a well-established risk factor, and at least one study has linked gum disease to a higher dementia risk. Or it might have to do with the simple mechanical act of chewing, reducing blood flow to the brain. A new study has directly investigated chewing ability in older adults.

The Swedish study, involving 557 older adults (77+), found that those with multiple tooth loss, and those who had difficulty chewing hard food such as apples, had a significantly higher risk of developing cognitive impairments (cognitive status was measured using the MMSE). However, when adjusted for sex, age, and education, tooth loss was no longer significant, but chewing difficulties remained significant.

In other words, what had caused the tooth loss didn’t matter. The important thing was to maintain chewing ability, whether with your own natural teeth or dentures.

This idea that the physical act of chewing might affect your cognitive function (on a regular basis; I don’t think anyone is suggesting that you’re brighter when you chew!) is an intriguing and unexpected one. It does, however, give even more emphasis to the importance of physical exercise, which is a much better way of increasing blood flow to the brain.

The finding also reminds us that there are many things going on in the brain that may deteriorate with age and thus lead to cognitive decline and even dementia.

A study using data from the Lothian Birth Cohort (people born in Scotland in 1936) has analyzed brain scans of 638 participants when they were 73 years old. Comparing this data with participants’ earlier reports of their exercise and leisure activities at age 70, it was found that those who reported higher levels of regular physical activity showed significantly less brain atrophy than those who did minimal exercise. Participation in social and mentally stimulating activities, on the other hand, wasn’t associated with differences in brain atrophy.

Regular physical exercise was also associated with fewer white matter lesions. While leisure activity was also associated with healthier white matter, this was not significant after factors such as age, social class, and health status were taken into account.

Unfortunately, this study is reported in a journal to which I don’t have access. I would love to have more details about the leisure activities data and the brain scans. However, although the failure to find a positive effect of stimulating activities is disappointing, it’s worth noting another recent study, that produced two relevant findings. First, men with high levels of cognitive activity showed a significant reduction in white matter lesions, while women did not. Women with high levels of cognitive activity, on the other hand, showed less overall brain atrophy — but men did not.

Secondly, both genders showed less atrophy in a particular region of the prefrontal cortex, but there was no effect on the hippocampus — the natural place to look for effects (and the region where physical exercise is known to have positive effects).

In other words, the positive effects of cognitive activity on the brain might be quite different from the positive effects of physical exercise.

The findings do, of course, add to the now-compelling evidence for the benefits of regular physical activity in fighting cognitive decline.

It’s good news, then, that a small study has found that even frail seniors can derive significant benefits from exercise.

The study involved 83 older adults (61-89), some of whom were considered frail. Forty-three took part in group exercises (3 times a week for 12 weeks), while 40 were wait-listed controls. Participants were assessed for physical capacity, quality of life and cognitive health a week before the program began, and at the end.

Those who took part in the exercise program significantly improved their physical capacity, cognitive performance, and quality of life. These benefits were equivalent among frail and non-frail participants.

Frailty is associated with a higher risk of falls, hospitalizations, cognitive decline and psychological distress, and, of course, increases with age. In the U.S, it’s estimated that 7% of seniors aged 65 to 74, 18% of those aged 75 to 84, and 37% of seniors over the age of 85 are frail.

I’ve reported before on the growing evidence that metabolic syndrome in middle and old age is linked to greater risk of cognitive impairment in old age and faster decline. A new study shows at least part of the reason.

The study involved 71 middle-aged people recruited from the Wisconsin Registry for Alzheimer's Prevention (WRAP), of whom 29 met the criteria for metabolic syndrome (multiple cardiovascular and diabetes risk factors including abdominal obesity, high blood pressure, high blood sugar and high cholesterol).

Those with metabolic syndrome averaged 15% less blood flow to the brain than those without the syndrome.

One tried and true method of increasing blood flow to the brain is of course through exercise.

The study was presented at the Alzheimer's Association International Conference in Vancouver, Canada by Barbara Bendlin.

The study involved 120 healthy older adults (60-79) from Shanghai, who were randomly assigned to one of four groups: one that participated in three sessions of tai chi every week for 40 weeks; another that instead had ‘social interaction’ sessions (‘lively discussions’); another in which participants engaged in walking around a track; and a non-intervention group included as a control. Brain scans were taken before and after the 40-week intervention, and cognitive testing took place at 20 weeks as well as these times.

Compared to those who received no intervention, both those who participated in tai chi, and those who participated in the social sessions, showed significant increases in brain volume and on some cognitive measures. However, the tai chi group showed improvement on more cognitive tests than the social group (on the Mattis Dementia Rating Scale, the Trailmaking Tests, delayed recognition on the Auditory Verbal Learning Test, and verbal fluency for animals vs verbal fluency and positive trends only on Trails A and the Auditory test).

Surprisingly, there were no such significant effects from the walking intervention, which involved 30 minutes of brisk walking around a 400m circular track, sandwiched by 10 minutes of warm-up and 10 minutes cool-down exercises. This took place in the same park as the tai chi sessions (which similarly included 20 minutes of warm-up exercises, 20 minutes of tai chi, and 10 minutes of cool-down exercises).

This finding is inconsistent with other research, but the answer seems to lie in individual differences — specifically, speed of walking. Faster walkers showed significantly better performance on the Stroop test, and on delayed recall and recognition on the Auditory Verbal Learning Test. It should be noted that, unlike some studies in which participants were encouraged to reach heart-rate targets, participants in this study were simply told to walk at their own speed. This finding, then, would seem to support the view that brisk walking is needed to reap good health and cognitive benefits (which shouldn’t put anyone off — anything is better than nothing! and speed is likely to come with practice, if that’s your aim).

It should also be noted that this population has generally high rates of walking. It is likely, then, that the additional walking in these sessions did not add a great deal to their existing behavior.

There is a caveat to the strongly positive effects of tai chi: this group showed lower cognitive performance at baseline. This was because the group randomly received more individuals with very low scores (8 compared with 5 in the other groups).

The study is, of course, quite a small one, and a larger study is required to confirm these results.

One final note: the relative differences in enjoyment were not explicitly investigated, but the researchers did note that the social group, who initially were given topics to discuss in their hour-long sessions, then decided to select and organize their own discussions, and have continued to do so for two years following the end of the study. It would have been nice if the researchers had re-tested participants at that point.

A study designed to compare the relative benefits of exercise and diet control on Alzheimer’s pathology and cognitive performance has revealed that while both are beneficial, exercise is of greater benefit in reducing Alzheimer’s pathology and cognitive impairment.

The study involved mice genetically engineered with a mutation in the APP gene (a familial risk factor for Alzheimer’s), who were given either a standard diet or a high-fat diet (60% fat, 20% carbohydrate, 20% protein vs 10% fat, 70% carbohydrate, 20% protein) for 20 weeks (from 2-3 to 7-8 months of age). Some of the mice on the high-fat diet spent the second half of that 20 weeks in an environmentally enriched cage (more than twice as large as the standard cage, and supplied with a running wheel and other objects). Others on the high-fat diet were put back on a standard diet in the second 10 weeks. Yet another group were put on a standard diet and given an enriched cage in the second 10 weeks.

Unsurprisingly, those on the high-fat diet gained significantly more weight than those on the standard diet, and exercise reduced that gain — but not as much as diet control (i.e., returning to a standard diet) did. Interestingly, this was not the result of changes in food intake, which either stayed the same or slightly increased.

More importantly, exercise and diet control were roughly equal in reversing glucose intolerance, but exercise was more effective than diet control in ameliorating cognitive impairment. Similarly, while amyloid-beta pathology was significantly reduced in both exercise and diet-control conditions, exercise produced the greater reduction in amyloid-beta deposits and level of amyloid-beta oligomers.

It seems that diet control improves metabolic disorders induced by a high-fat diet — conditions such as obesity, hyperinsulinemia and hypercholesterolemia — which affects the production of amyloid-beta. However exercise is more effective in tackling brain pathology directly implicated in dementia and cognitive decline, because it strengthens the activity of an enzyme that decreases the level of amyloid-beta.

Interestingly, and somewhat surprisingly, the combination of exercise and diet control did not have a significantly better effect than exercise alone.

The finding adds to the growing pile of evidence for the value of exercise in maintaining a healthy brain in later life, and helps explain why. Of course, as I’ve discussed on several occasions, we already know other mechanisms by which exercise improves cognition, such as boosting neurogenesis.

More findings from the long-running Mayo Clinic Study of Aging reveal that using a computer plus taking moderate exercise reduces your risk of mild cognitive impairment significantly more than you would expect from simply adding together these two beneficial activities.

The study involved 926 older adults (70-93), of whom 109 (12%) were diagnosed with MCI. Participants completed questionnaires on physical exercise and mental stimulation within the previous year. Computer use was targeted in this analysis because of its popularity as a cognitive activity, and because it was particularly associated with reduced odds of having MCI.

Among the cognitively healthy, only 20.1% neither exercised moderately nor used a computer, compared to 37.6% of those with MCI. On the other hand, 36% of the cognitively healthy both exercised and used a computer, compared to only 18.3% of those with MCI. There was little difference between the two groups as regards exercise but no computer use, or computer use but no exercise.

The analysis took into account calorie intake, as well as education, depression, and other health factors. Daily calorie intake was significantly higher in those with MCI compared to those without (respective group medians of 2100 calories vs 1802) — note that the median BMI was the same for the two groups.

Moderate physical exercise was defined as brisk walking, hiking, aerobics, strength training, golfing without a golf cart, swimming, doubles tennis, yoga, martial arts, using exercise machines and weightlifting. Light exercise included activities such as bowling, leisurely walking, stretching, slow dancing, and golfing with a cart. Mentally stimulating activities included reading, crafts, computer use, playing games, playing music, group and social and artistic activities and watching less television.

It should be noted that the assessment of computer activities was very basic. The researchers suggest that in future studies, both duration and frequency should be assessed. I would add type of activity, although that would be a little more difficult to assess.

Overall, the findings add yet more weight to the evidence for the value of physical exercise and mental stimulation in staving off cognitive impairment in old age, and add the twist that doing both is much better than doing either one alone.

I’ve talked before about Dr Berman’s research into Attention Restoration Theory, which proposes that people concentrate better after nature walks or even just looking at nature scenes. In his latest study, the findings have been extended to those with clinical depression.

The study involved 20 young adults (average age 26), all of whom had a diagnosis of major depressive disorder. Short-term memory and mood were assessed (using the backwards digit span task and the PANAS), and then participants were asked to think about an unresolved, painful autobiographical experience. They were then randomly assigned to go for a 50-minute walk along a prescribed route in either the Ann Arbor Arboretum (woodland park) or traffic heavy portions of downtown Ann Arbor. After the walk, mood and cognition were again assessed. A week later the participants repeated the entire procedure in the other location.

Participants exhibited a significant (16%) increase in attention and working memory after the nature walk compared to the urban walk. While participants felt more positive after both walks, there was no correlation with memory effects.

The finding is particularly interesting because depression is characterized by high levels of rumination and negative thinking. It seemed quite likely, then, that a solitary walk in the park might make depressed people feel worse, and worsen working memory. It’s intriguing that it didn’t.

It’s also worth emphasizing that, as in earlier studies, this effect of nature on cognition appears to be independent of mood (which is, of course, the basic tenet of Attention Restoration Theory).

Of course, this study is, like the others, small, and involves the same demographic. Hopefully future research will extend the sample groups, to middle-aged and older adults.

I’ve mentioned before that, for some few people, exercise doesn’t seem to have a benefit, and the benefits of exercise for fighting age-related cognitive decline may not apply to those carrying the Alzheimer’s gene.

New research suggests there is another gene variant that may impact on exercise’s effects. The new study follows on from earlier research that found that physical exercise during adolescence had more durable effects on object memory and BDNF levels than exercise during adulthood. In this study, 54 healthy but sedentary young adults (aged 18-36) were given an object recognition test before participating in either (a) a 4-week exercise program, with exercise on the final test day, (b) a 4-week exercise program, without exercise on the final test day, (c) a single bout of exercise on the final test day, or (d) remaining sedentary between test days.

Exercise both improved object recognition memory and reduced perceived stress — but only in one group: those who exercised for 4 weeks including the final day of testing. In other words, both regular exercise and recent exercise was needed to produce a memory benefit.

But there is one more factor — and this is where it gets really interesting — the benefit in this group didn’t happen for every member of the group. Only those carrying a specific genotype benefited from regular and recent exercise. This genotype has to do with the brain protein BDNF, which is involved in neurogenesis and synaptic plasticity, and which is increased by exercise. The BDNF gene comes in two flavors: Val and Met. Previous research has linked the less common Met variant to poorer memory and greater age-related cognitive decline.

In other words, it seems that the Met allele affects how much BDNF is released as a result of exercise, and this in turn affects cognitive benefits.

The object recognition test involved participants seeing a series of 50 images (previously selected as being highly recognizable and nameable), followed by a 15 minute filler task, before seeing 100 images (the previous 50 and 50 new images) and indicating which had been seen previously. The filler task involved surveys for state anxiety, perceived stress, and mood. On the first (pre-program) visit, a survey for trait anxiety was also completed.

Of the 54 participants, 31 carried two copies of the Val allele, and 23 had at least one Met allele (19 Val/Met; 4 Met/Met). The population frequency for carrying at least one Met allele is 50% for Asians, 30% in Caucasians, and 4% in African-Americans.

Although exercise decreased stress and increased positive mood, the cognitive benefits of exercise were not associated with mood or anxiety. Neither was genotype associated with mood or anxiety. However, some studies have found an association between depression and the Met variant, and this study is of course quite small.

A final note: this study is part of research looking at the benefits of exercise for children with ADHD. The findings suggest that genotyping would enable us to predict whether an individual — a child with ADHD or an older adult at risk of cognitive decline or impairment — would benefit from this treatment strategy.

A number of studies, principally involving rodents, have established that physical exercise stimulates the creation of new brain cells in the hippocampus. A recent study attempted to uncover more about the mechanism.

Using two drugs that work directly on muscles, producing the physical effects of exercise, the researchers compared the effects on the brain. One drug (Aicar) improves the fitness of even sedentary animals. The other drug increases the effects of exercise on animals that exercise, but has little effect on sedentary animals.

After a week of receiving one of the drugs, sedentary mice performed better on tests of memory and learning, and showed more new brain cells. These effects were significantly greater for those taking Aicar.

Because the drugs have very little ability to cross into the brain, this demonstrates that the neurogenesis results from exercise-type reactions in the muscles, not to brain responses to the drugs. Indeed, previous research has found that direct infusion of Aicar into the brain impaired learning and memory.

Aicar increases the muscles’ output of AMPK, an enzyme that affects cellular energy and metabolism. It’s speculated that some of this enzyme may enter the bloodstream and travel to the brain. Interestingly, as with neurogenesis, AMPK activity in muscles appears to decline with age. It may be that AMPK production could serve as a biomarker for neurogenesis, as well as being a target for improving neurogenesis.

These findings add weight to evidence for the value of aerobic exercise over other types of exercise (given that the mice exercise by running). However, I see that human research has found that resistance training (which is difficult to study in mice!) also increases AMPK activity.

Do note — if you are hopeful that drugs will relieve you of the need to exercise — that the benefits were not only smaller than those achieved from exercise, but also didn’t last. In those mice taking Aicar for a second week, their brains not only stopped deriving any benefit, but actually deteriorated.

A study involving 86 older women (aged 70-80) with probable MCI has compared the effectiveness of resistance and aerobic training in improving executive function. The women were randomly allocated either to resistance training, aerobic training, or balance and tone training (control group). The programs all ran twice weekly for six months.

The study found that resistance training significantly improved performance on the Stroop Test and also the associative memory task. These improvements were associated with changes in some brain regions. In contrast to previous studies in healthy older adults, aerobic training didn’t produce any significant cognitive improvement, although it did produce significantly better balance and mobility, and cardiovascular capacity, compared to the control.

Interestingly, a previous study from these researchers demonstrated that it took a year of resistance training to achieve such results in cognitively healthy women aged 65-75. This suggests that the benefits may be greater for those at greater risk.

It may be that the greater benefits of resistance training over aerobic training are not be solely due to physical differences in the exercise. The researchers point out that resistance training required more cognitive engagement (“If you’re lifting weights you have to monitor your sets, your reps, you use weight machines and you have to adjust the seat, etc.”) compared to walking.

Note that impaired associative memory is one of the earliest cognitive functions affected in Alzheimer’s.

It’s also worth noting that exercise compliance was low (55-60%), suggesting that benefits might have been greater if the participants had been more motivated — or found the programs more enjoyable! The failure of aerobic exercise to improve cognition is somewhat surprising, and perhaps it, too, may be attributed to insufficient engagement — in terms of intensity as well as amount.

The researchers have put up a YouTube video of the resistance training exercises used in the study.

A four-year study involving 716 elderly (average age 82) has revealed that those who were most physically active were significantly less likely to develop Alzheimer’s than those least active. The study is unique in that, in addition to self-reports of physical and social activity, activity was objectively measured (for up to 10 days) through a device worn on the wrist. This device (an actigraph) enabled everyday activity, such as cooking, washing the dishes, playing cards and even moving a wheelchair with a person's arms, to be included in the analysis.

The study found that those in the bottom 10% of daily physical activity were more than twice as likely (2.3 times) to develop Alzheimer's disease as those in the top 10%. Those in the bottom 10% of intensity of physical activity were almost three times (2.8 times) as likely to develop Alzheimer's disease as people in the top 10%.

Moreover, the level of activity was associated with the rate of cognitive decline.

The association remained after motor function, depression, chronic health conditions, and APOE gene status were taken into account.

The findings should encourage anyone who feels that physical exercise is beyond them to nevertheless engage in milder forms of daily activity.

Addendum:

Another recent study, involving 331 cognitively healthy elderly, has also found that higher levels of physical activity were associated with better cognitive performance (specifically, a shorter time to complete the Trail-making test, and higher levels of verbal fluency) and less brain atrophy. Activity levels were based on the number of self-reported light and hard activities for at least 30 minutes per week. Participants were assessed in terms of MMSE score, verbal fluency, and visuospatial ability.

Following on from research showing an association between lower walking speed and increased risk of dementia, and weaker hand grip strength and increased dementia risk, a large study has explored whether this association extends to middle-aged and younger-old adults.

Part of the long-running Framingham study, the study involved 2,410 men and women with an average age of 62, who underwent brain scans and tests for walking speed, hand grip strength and cognitive function. During the follow-up period of up to 11 years, 34 people (1.4%) developed dementia (28 Alzheimer’s) and 79 people (3.3%) had a stroke.

Those who had a slower walking speed at the start of the study were one-and-a-half times more likely to develop dementia compared to people with faster walking speed, while stronger hand grip strength was associated with a 42% lower risk of stroke or transient ischemic attack in people over age 65.

While the nature of the association is not yet understood, the findings do seem to support the benefits of physical fitness. At the least, these physical attributes can serve as pointers to the need for more investigation of an older person’s brain health. But they might also serve as a warning to improve physical fitness.

A review of 10 observational and four intervention studies as said to provide strong evidence for a positive relationship between physical activity and academic performance in young people (6-18). While only three of the four intervention studies and three of the 10 observational studies found a positive correlation, that included the two studies (one intervention and one observational) that researchers described as “high-quality”.

An important feature of the high-quality studies was that they used objective measures of physical activity, rather than students' or teachers' reports. More high-quality studies are clearly needed. Note that the quality score of the 14 studies ranged from 22%! to 75%.

Interestingly, a recent media report (NOT, I hasten to add, a peer-reviewed study appearing in an academic journal) spoke of data from public schools in Lincoln, Nebraska, which apparently has a district-wide physical-fitness test, which found that those were passed the fitness test were significantly more likely to also pass state reading and math tests.

Specifically, data from the last two years apparently shows that 80% of the students who passed the fitness test either met or exceeded state standards in math, compared to 66% of those who didn't pass the fitness test, and 84% of those who passed the fitness test met or exceeded state standards in reading, compared to 71% of those who failed the fitness test.

Another recent study looks at a different aspect of this association between physical exercise and academic performance.

The Italian study involved138 normally-developing children aged 8-11, whose attention was tested before and after three different types of class: a normal academic class; a PE class focused on cardiovascular endurance and involving continuous aerobic circuit training followed by a shuttle run exercise; a PE class combining both physical and mental activity by involving novel use of basketballs in varying mini-games that were designed to develop coordination and movement-based problem-solving. These two types of physical activity offered the same exercise intensity, but very different skill demands.

The attention test was a short (5-minute) paper-and-pencil task in which the children had to mark each occurrence of “d” with double quotation marks either above or below in 14 lines of randomly mixed p and d letters with one to four single and/or double quotation marks either over and/or under each letter.

Processing speed increased 9% after mental exercise (normal academic class) and 10% after physical exercise. These were both significantly better than the increase of 4% found after the combined physical and mental exertion.

Similarly, scores on the test improved 13% after the academic class, 10% after the standard physical exercise, and only 2% after the class combining physical and mental exertion.

Now it’s important to note is that this is of course an investigation of the immediate arousal benefits of exercise, rather than an investigation of the long-term benefits of being fit, which is a completely different question.

But the findings do bear on the use of PE classes in the school setting, and the different effects that different types of exercise might have.

First of all, there’s the somewhat surprising finding that attention was at least as great, if not better, after an academic class than the PE class. It would not have been surprising if attention had flagged. It seems likely that what we are seeing here is a reflection of being in the right head-space — that is, the advantage of continuing with the same sort of activity.

But the main finding is the, also somewhat unexpected, relative drop in attention after the PE class that combined mental and physical exertion.

It seems plausible that the reason for this lies in the cognitive demands of the novel activity, which is, I think, the main message we should take away from this study, rather than any comparison between physical and mental activity. However, it would not be surprising if novel activities that combine physical and mental skills tend to be more demanding than skills that are “purely” (few things are truly pure I know) one or the other.

Of course, it shouldn’t be overlooked that attention wasn’t hampered by any of these activities!

We know that physical exercise greatly helps you prevent cognitive decline with aging. We know that mental stimulation also helps you prevent age-related cognitive decline. So it was only a matter of time before someone came up with a way of combining the two. A new study found that older adults improved executive function more by participating in virtual reality-enhanced exercise ("exergames") that combine physical exercise with computer-simulated environments and interactive videogame features, compared to the same exercise without the enhancements.

The Cybercycle Study involved 79 older adults (aged 58-99) from independent living facilities with indoor access to a stationary exercise bike. Of the 79, 63 participants completed the three-month study, meaning that they achieved at least 25 rides during the three months.

Unfortunately, randomization was not as good as it should have been — although the researchers planned to randomize on an individual basis, various technical problems led them to randomize on a site basis (there were eight sites), with the result that the cybercycle group and the control bike group were significantly different in age and education. Although the researchers took this into account in the analysis, that is not the same as having groups that match in these all-important variables. However, at least the variables went in opposite directions: while the cybercycle group was significantly younger (average 75.7 vs 81.6 years), it was significantly less educated (average 12.6 vs 14.8 years).

Perhaps also partly off-setting the age advantage, the cybercycle group was in poorer shape than the control group (higher BMI, glucose levels, lower physical activity level, etc), although these differences weren’t statistically significant. IQ was also lower for the cybercycle group, if not significantly so (but note the high averages for both groups: 117.6 vs 120.6). One of the three tests of executive function, Color Trails, also showed a marked group difference, but the large variability in scores meant that this difference was not statistically significant.

Although participants were screened for disorders such as Alzheimer’s and Parkinson’s, and functional disability, many of both groups were assessed as having MCI — 16 of the 38 in the cybercycle group and 14 of the 41 in the control bike group.

Participants were given cognitive tests at enrolment, one month later (before the intervention began), and after the intervention ended. The stationary bikes were identical for both groups, except the experimental bike was equipped with a virtual reality display. Cybercycle participants experienced 3D tours and raced against a "ghost rider," an avatar based on their last best ride.

The hypothesis was that cybercycling would particularly benefit executive function, and this was borne out. Executive function (measured by the Color Trails, Stroop test, and Digits Backward) improved significantly more in the cybercycle condition, and indeed was the only cognitive task to do so (other cognitive tests included verbal fluency, verbal memory, visuospatial skill, motor function). Indeed, the control group, despite getting the same amount of exercise, got worse at the Digits Backward test, and failed to show any improvement on the Stroop test.

Moreover, significantly fewer cybercyclists progressed to MCI compared to the control group (three vs nine).

There were no differences in exercise quantity or quality between the two groups — which does argue against the idea that cyber-enhanced physical activity would be more motivating. However, the cybercycling group did tend to comment on their enjoyment of the exercise. While the enjoyment may not have translated into increased activity in this situation, it may well do so in a longer, less directed intervention — i.e. real life.

It should also be remembered that the intervention was relatively short, and that other cognitive tasks might take longer to show improvement than the more sensitive executive function. This is supported by the fact that levels of the brain growth factor BDNF, assessed in 30 participants, showed a significantly greater increase of BDNF in cybercyclists.

I should also emphasize that the level of physical exercise really wasn't that great, but nevertheless the size of the cybercycle's effect on executive function was greater than usually produced by aerobic exercise (a medium effect rather than a small one).

The idea that activities that combine physical and mental exercise are of greater cognitive benefit than the sum of benefits from each type of exercise on its own is not inconsistent with previous research, and in keeping with evidence from animal studies that physical exercise and mental stimulation help the brain via different mechanisms. Moreover, I have an idea that enjoyment (in itself, not as a proxy for motivation) may be a factor in the cognitive benefits derived from activities, whether physical or mental. Mere speculation, derived from two quite separate areas of research: the idea of “flow” / “being in the zone”, and the idea that humor has physiological benefits.

Of course, as discussed, this study has a number of methodological issues that limit its findings, but hopefully it will be the beginning of an interesting line of research.

Why is diabetes associated with cognitive impairment and even dementia in older adults? New research pinpoints two molecules that trigger a cascade of events that end in poor blood flow and brain atrophy.

The study involved 147 older adults (average age 65), of whom 71 had type 2 diabetes and had been taking medication to manage it for at least five years. Brain scans showed that the diabetic patients had greater blood vessel constriction than the age- and sex-matched controls, and more brain atrophy. The reduction in brain tissue was most marked in the grey matter in the parietal and occipital lobes and cerebellum. Research has found that, at this age, while the average brain shrinks by about 1% annually, a diabetic brain might shrink by as much as 15%. Diabetics also had more white matter hyperintensities in the temporal, parietal and occipital lobes.

Behaviorally, the diabetics also had greater depression, slower walking, and executive dysfunction.

The reduced performance of blood vessels (greater vasoconstriction, blunted vasodilatation), and increased brain atrophy in the frontal, temporal, and parietal lobes, was associated with two adhesion molecules – sVCAM and sICAM. White matter hyperintensities were not associated with the adhesion molecules, inflammatory markers, or blood vessel changes.

It seems that the release of these molecules, probably brought about by chronic hyperglycemia and insulin resistance, produces chronic inflammation, which in turn brings about constricted blood vessels, reduced blood flow, and finally loss of neurons. The blood vessel constriction and the brain atrophy were also linked to higher glucose levels.

The findings suggest that these adhesion molecules provide two biomarkers of vascular health that could enable clinicians to recognize impending brain damage, that could then perhaps be prevented.

The findings also add weight to the growing evidence that diabetes management is crucial in preventing cognitive decline.

In the last five years, three studies have linked lower neighborhood socioeconomic status to lower cognitive function in older adults. Neighborhood has also been linked to self-rated health, cardiovascular disease, and mortality. Such links between health and neighborhood may come about through exposure to pollutants or other environmental stressors, access to alcohol and cigarettes, barriers to physical activity, reduced social support, and reduced access to good health and social services.

Data from the large Women’s Health Initiative Memory Study has now been analyzed to assess whether the relationship between neighborhood socioeconomic status can be explained by various risk and protective factors for poor cognitive function.

Results confirmed that higher neighborhood socioeconomic status was associated with higher cognitive function, even after individual factors such as age, ethnicity, income, education, and marital status have been taken into account. A good deal of this was explained by vascular factors (coronary heart disease, diabetes, stroke, hypertension), health behaviors (amount of alcohol consumed, smoking, physical activity), and psychosocial factors (depression, social support). Nevertheless, the association was still (barely) significant after these factors were taken account of, suggesting some other factors may also be involved. Potential factors include cognitive activity, diet, and access to health services.

In contradiction of earlier research, the association appeared to be stronger among younger women. Consistent with other research, the association was stronger for non-White women.

Data from 7,479 older women (65-81) was included in the analysis. Cognitive function was assessed by the Modified MMSE (3MSE). Neighborhood socioeconomic status was assessed on the basis of: percentage of adults over 25 with less than a high school education, percentage of male unemployment, percentage of households below the poverty line, percentage of households receiving public assistance, percentage of female-headed households with children, and median household income. Around 87% of participants were White, 7% Black, 3% Hispanic, and 3% other. Some 92% had graduated high school, and around 70% had at least some college.

In the first mouse study, when young and old mice were conjoined, allowing blood to flow between the two, the young mice showed a decrease in neurogenesis while the old mice showed an increase. When blood plasma was then taken from old mice and injected into young mice, there was a similar decrease in neurogenesis, and impairments in memory and learning.

Analysis of the concentrations of blood proteins in the conjoined animals revealed the chemokine (a type of cytokine) whose level in the blood showed the biggest change — CCL11, or eotaxin. When this was injected into young mice, they indeed showed a decrease in neurogenesis, and this was reversed once an antibody for the chemokine was injected. Blood levels of CCL11 were found to increase with age in both mice and humans.

The chemokine was a surprise, because to date the only known role of CCL11 is that of attracting immune cells involved in allergy and asthma. It is thought that most likely it doesn’t have a direct effect on neurogenesis, but has its effect through, perhaps, triggering immune cells to produce inflammation.

Exercise is known to at least partially reverse loss of neurogenesis. Exercise has also been shown to produce chemicals that prevent inflammation. Following research showing that exercise after brain injury can help the brain repair itself, another mouse study has found that mice who exercised regularly produced interleukin-6 (a cytokine involved in immune response) in the hippocampus. When the mice were then exposed to a chemical that destroys the hippocampus, the interleukin-6 dampened the harmful inflammatory response, and prevented the loss of function that is usually observed.

One of the actions of interleukin-6 that brings about a reduction in inflammation is to inhibit tumor necrosis factor. Interestingly, I previously reported on a finding that inhibiting tumor necrosis factor in mice decreased cognitive decline that often follows surgery.

This suggests not only that exercise helps protect the brain from the damage caused by inflammation, but also that it might help protect against other damage, such as that caused by environmental toxins, injury, or post-surgical cognitive decline. The curry spice cucurmin, and green tea, are also thought to inhibit tumor necrosis factor.

A three-year study following 1,262 healthy older Canadians (aged 67-84) has found that, among those who exercised little, those who had high-salt diets showed significantly greater cognitive decline. On the bright side, sedentary older adults who had low-salt consumption did not show cognitive decline over the three years. And those who had higher levels of physical activity did not show any association between salt and cognition.

Low sodium intake is associated with reduced blood pressure and risk of heart disease, adding even more weight to the mantra: what’s good for the heart is good for the brain.

The analysis controlled for age, sex, education, waist circumference, diabetes, and dietary intakes. Salt intake was based on a food frequency questionnaire. Low sodium intake was defined as not exceeding 2,263 mg/day; mid sodium intake 3,090 mg/day; and high sodium intake 3,091 and greater mg/day. A third of the participants fell into each group. Physical activity was also measured by a self-reported questionnaire (Physical Activity Scale for the Elderly). Cognitive function was measured by the Modified MMSE.

And adding to the evidence that exercise is good for you (not that we really need any more!), a rat study has found that aging rats that ran just over half a kilometer each week were protected against long-term memory loss that can happen suddenly following bacterial infection.

Previous research found that older rats experienced memory loss following E. coli infection, but young adult rats did not. In the older animals, microglia (the brain’s immune cells) were more sensitive to infection, releasing greater quantities of inflammatory molecules called cytokines in the hippocampus. This exaggerated response brought about impairments in synaptic plasticity (the neural changes that underlie learning) and reductions in BDNF.

In this study, the rats were given unlimited access to running wheels. Although the old rats only ran an average of 0.43 miles per week (50 times less distance than the young rats), they performed better on a memory test than rats who only had access to a locked exercise wheel. Moreover, the runners performed as well on the memory test as rats that were not exposed to E. coli.

The researchers are now planning to examine the role that stress hormones may play in sensitizing microglia, and whether physical exercise slows these hormones in older rats.

I’ve always felt that better thinking was associated with my brain working ‘in a higher gear’ — literally working at a faster rhythm. So I was particularly intrigued by the findings of a recent mouse study that found that brainwaves associated with learning became stronger as the mice ran faster.

In the study, 12 male mice were implanted with microelectrodes that monitored gamma waves in the hippocampus, then trained to run back and forth on a linear track for a food reward. Gamma waves are thought to help synchronize neural activity in various cognitive functions, including attention, learning, temporal binding, and awareness.

We know that the hippocampus has specialized ‘place cells’ that record where we are and help us navigate. But to navigate the world, to create a map of where things are, we need to also know how fast we are moving. Having the same cells encode both speed and position could be problematic, so researchers set out to find how speed was being encoded. To their surprise and excitement, they found that the strength of the gamma rhythm grew substantially as the mice ran faster.

The results also confirmed recent claims that the gamma rhythm, which oscillates between 30 and 120 times a second, can be divided into slow and fast signals (20-45 Hz vs 45-120 Hz for mice, consistent with the 30-55 Hz vs 45-120 Hz bands found in rats) that originate from separate parts of the brain. The slow gamma waves in the CA1 region of the hippocampus were synchronized with slow gamma waves in CA3, while the fast gamma in CA1 were synchronized with fast gamma waves in the entorhinal cortex.

The two signals became increasingly separated with increasing speed, because the two bands were differentially affected by speed. While the slow waves increased linearly, the fast waves increased logarithmically. This differential effect could have to do with mechanisms in the source regions (CA3 and the medial entorhinal cortex, respectively), or to mechanisms in the different regions in CA1 where the inputs terminate (the waves coming from CA3 and the entorhinal cortex enter CA1 in different places).

In the hippocampus, gamma waves are known to interact with theta waves. Further analysis of the data revealed that the effects of speed on gamma rhythm only occurred within a narrow range of theta phases — but this ‘preferred’ theta phase also changed with running speed, more so for the slow gamma waves than the fast gamma waves (which is not inconsistent with the fact that slow gamma waves are more affected by running speed than fast gamma waves). Thus, while slow and fast gamma rhythms preferred similar phases of theta at low speeds, the two rhythms became increasingly phase-separated with increasing running speed.

What’s all this mean? Previous research has shown that if inputs from CA3 and the entorhinal cortex enter CA1 at the same time, the kind of long-term changes at the synapses that bring about learning are stronger and more likely in CA1. So at low speeds, synchronous inputs from CA3 and the entorhinal cortex at similar theta phases make them more effective at activating CA1 and inducing learning. But the faster you move, the more quickly you need to process information. The stronger gamma waves may help you do that. Moreover, the theta phase separation of slow and fast gamma that increases with running speed means that activity in CA3 (slow gamma source) increasingly anticipates activity in the medial entorhinal cortex (fast gamma source).

What does this mean at the practical level? Well at this point it can only be speculation that moving / exercising can affect learning and attention, but I personally am taking this on board. Most of us think better when we walk. This suggests that if you’re having trouble focusing and don’t have time for that, maybe walking down the hall or even jogging on the spot will help bring your brain cells into order!

Pushing speculation even further, I note that meditation by expert meditators has been associated with changes in gamma and theta rhythms. And in an intriguing comparison of the effect of spoken versus sung presentation on learning and remembering word lists, the group that sang showed greater coherence in both gamma and theta rhythms (in the frontal lobes, admittedly, but they weren’t looking elsewhere).

So, while we’re a long way from pinning any of this down, it may be that all of these — movement, meditation, music — can be useful in synchronizing your brain rhythms in a way that helps attention and learning. This exciting discovery will hopefully be the start of an exploration of these possibilities.

Another study showing the value of exercise for preserving your mental faculties in old age. This time it has to do with the development of small brain lesions or infarcts called "silent strokes." Don’t let the words “small” and “silent” fool you — these lesions have been linked to memory problems and even dementia, as well as stroke, an increased risk of falls and impaired mobility.

The study involved 1,238 people taken from the Northern Manhattan Study, a long-running study looking at stroke and vascular problems in a diverse community. Their brains were scanned some six years after completing an exercise questionnaire, when they were an average of 70 years old. The scans found that 16% of the participants had these small brain lesions.

Those who had reported engaging in moderate to intense exercise were 40% less likely to have these infarcts compared to people who did no regular exercise. Depressingly, there was no significant difference between those who engaged in light exercise and those who didn’t exercise (which is not to say that light exercise doesn’t help in other regards! a number of studies have pointed to the value of regular brisk walking for fighting cognitive decline). This is consistent with earlier findings that only the higher levels of activity consistently protect against stroke.

The results remained the same after other vascular risk factors such as high blood pressure, high cholesterol and smoking, were accounted for. Of the participants, 43% reported no regular exercise; 36% engaged in regular light exercise (e.g., golf, walking, bowling or dancing); 21% engaged in regular moderate to intense exercise (e.g., hiking, tennis, swimming, biking, jogging or racquetball).

However, there was no association with white matter lesions, which have also been associated with an increased risk of stroke and dementia.

Moreover, this effect was not seen among those with Medicaid or no health insurance, suggesting that lower socioeconomic status (or perhaps poorer access to health care) is associated with negative factors that counteract the benefits of exercise. Previous research has found that lower SES is associated with higher cardiovascular disease regardless of access to care.

Of the participants, 65% were Hispanic, 17% non-Hispanic black, and 15% non-Hispanic white. Over half (53%) had less than high school education, and 47% were on Medicaid or had no health insurance.

It wasn’t so long ago we believed that only young brains could make neurons, that once a brain was fully matured all it could do was increase its connections. Then we found out adult brains could make new neurons too (but only in a couple of regions, albeit critical ones). Now we know that neurogenesis in the hippocampus is vital for some operations, and that the production of new neurons declines with age (leading to the idea that the reduction in neurogenesis may be one reason for age-related cognitive decline).

What we didn’t know is why this happens. A new study, using mice genetically engineered so that different classes of brain cells light up in different colors, has now revealed the life cycle of stem cells in the brain.

Adult stem cells differentiate into progenitor cells that ultimately give rise to mature neurons. It had been thought that the stem cell population remained stable, but that these stem cells gradually lose their ability to produce neurons. However, the mouse study reveals that during the mouse's life span, the number of brain stem cells decreased 100-fold. Although the rate of this decrease actually slows with age, and the output per cell (the number of progenitor cells each stem cell produces) increases, nevertheless the pool of stem cells is dramatically reduced over time.

The reason this happens (and why it wasn’t what we expected) is explained in a computational model developed from the data. It seems that stem cells in the brain differ from other stem cells. Adult stem cells in the brain wait patiently for a long time until they are activated. They then undergo a series of rapid divisions that give rise to progeny that differentiate into neurons, before ‘retiring’ to become astrocytes. What this means is that, unlike blood or gut stem cells (that renew themselves many times), brain stem cells are only used once.

This raises a somewhat worrying question: if we encourage neurogenesis (e.g. by exercise or drugs), are we simply using up stem cells prematurely? The researchers suggest the answer depends on how the neurogenesis has been induced. Parkinson's disease and traumatic brain injury, for example, activate stem cells directly, and so may reduce the stem cell population. However, interventions such as exercise stimulate the progenitor cells, not the stem cells themselves.

A recent study of cancer survivors has found that many survivors still suffer moderate to severe problems with pain, fatigue, sleep, memory and concentration three to five years after treatment has ended.

The study included 248 survivors of breast, colorectal, lung and prostate cancer. The survivors were primarily female and white, and most were more than five years post-diagnosis. Cognitive difficulties were reported by 13%. The other most common symptoms were fatigue (16%), disturbed sleep (15%), and pain (13%). Two assessments were made, one month apart. The similar results indicate these symptoms tend to be chronic.

The researchers pointed to the need for education programs to help survivors transition from treatment to life as a cancer survivor, and the need for clinicians and researchers to develop better ways to address sleep problems, fatigue and lasting difficulties with memory and concentration.

One activity that could be part of a post-treatment program is t'ai chi. A recent pilot study involving 23 women with a history of chemotherapy has found better cognitive and physical functioning after 10 weeks participating in a 60-minute t’ai chi class twice a week. Before and after the intervention, participants completed tests of memory, executive functioning, language, and attention, as well as tests of balance and self-report questionnaires of neuropsychological complaints, stress and mood, and fatigue.

However, though I’m a big fan of t’ai chi, I do have to note that without a control group, allowing the passing of time and the effects of any sort of group activity to be taken into account, it’s hard to draw any real conclusions from this.

Still, some support for this finding can be found in a recent meta-analysis of research investigating the benefits of t'ai chi for any improvement of medical conditions or clinical symptoms. This review found that the only clear evidence is in relation to fall prevention and improving psychological health. So, only middling support for t'ai chi, but the affirmation of its benefit for psychological health does support the potential value of this meditational practice for cancer survivors.

The findings of the first study were presented June 4 at the 2011 American Society of Clinical Oncology Annual Meeting in Chicago.

Following previous research suggesting that the volume of the hippocampus was reduced in some people with chronic PTSD, a twin study indicated that this may not be simply a sign that stress has shrunk the hippocampus, but that those with a smaller hippocampus are at greater risk of PTSD. Now a new study has found that Gulf War veterans who recovered from PTSD had, on average, larger hippocampi than veterans who still suffer from PTSD. Those who recovered had hippocampi of similar size to control subjects who had never had PTSD.

The study involved 244 Gulf War veterans, of whom 82 had lifetime PTSD, 44 had current PTSD, and 38 had current depression.

Because we don’t know hippocampal size prior to trauma, the findings don’t help us decide whether hippocampal size is a cause or an effect (or perhaps it would be truer to say, don’t help us decide the relative importance of these factors, because it seems most plausible that both are significant).

The really important question, of course, is whether an effective approach to PTSD treatment would be to work on increasing hippocampal volume. Exercise and mental stimulation, for example, are known to increase the creation of new brain cells in the hippocampus. In this case, the main mediator is probably the negative effects of stress (which reduces neurogenesis). There is some evidence that antidepressant treatment might increase hippocampal volume in people with PTSD.

The other conclusion we can derive from these findings is that perhaps we should not simply think of building hippocampal volume / creating new brain cells as a means of building cognitive reserve, thus protecting us from cognitive decline and dementia. We should also think of it as a means of improving our emotional resilience and protecting us from the negative effects of stress and trauma.

The new label of ‘metabolic syndrome’ applies to those having three or more of the following risk factors: high blood pressure, excess belly fat, higher than normal triglycerides, high blood sugar and low high-density lipoprotein (HDL) cholesterol (the "good" cholesterol). Metabolic syndrome has been linked to increased risk of heart attack.

A new French study, involving over 7,000 older adults (65+) has found that those with metabolic syndrome were 20% more likely to show cognitive decline on a memory test (MMSE) over a two or four year interval. They were also 13% more likely to show cognitive decline on a visual working memory test. Specifically, higher triglycerides and low HDL cholesterol were linked to poorer memory scores; diabetes (but not higher fasting blood sugar) was linked to poorer visual working memory and word fluency scores.

The findings point to the importance of managing the symptoms of metabolic syndrome.

High cholesterol and blood pressure in middle age tied to early memory problems

Another study, involving some 4800 middle-aged adults (average age 55), has found that those with higher cardiovascular risk were more likely to have lower cognitive function and a faster rate of cognitive decline over a 10-year period. A 10% higher cardiovascular risk was associated not only with increased rate of overall mental decline, but also poorer cognitive test scores in all areas except reasoning for men and fluency for women.

The cardiovascular risk score is based on age, sex, HDL cholesterol, total cholesterol, systolic blood pressure and whether participants smoked or had diabetes.

Memory problems may be sign of stroke risk

A very large study (part of the REGARDS study) tested people age 45 and older (average age 67) who had never had a stroke. Some 14,842 people took a verbal fluency test, and 17,851 people took a word recall memory test. In the next 4.5 years, 123 participants who had taken the verbal fluency test and 129 participants who had taken the memory test experienced a stroke.

Those who had scored in the bottom 20% for verbal fluency were 3.6 times more likely to develop a stroke than those who scored in the top 20%. For the memory test, those who scored in the bottom 20% were 3.5 times more likely to have a stroke than those in the top quintile.

The effect was greatest at the younger ages. At age 50, those who scored in the bottom quintile of the memory test were 9.4 times more likely to later have a stroke than those in the top quintile.

Together, these studies, which are consistent with many previous studies, confirm that cardiovascular problems and diabetes add to the risk of greater cognitive decline (and possible dementia) in old age. And point to the importance of treating these problems as soon as they appear.

A study involving 171 sedentary, overweight 7- to 11-year-old children has found that those who participated in an exercise program improved both executive function and math achievement. The children were randomly selected either to a group that got 20 minutes of aerobic exercise in an after-school program, one that got 40 minutes of exercise in a similar program, or a group that had no exercise program. Those who got the greater amount of exercise improved more. Brain scans also revealed increased activity in the prefrontal cortex and reduced activity in the posterior parietal cortex, for those in the exercise group.

The program lasted around 13 weeks. The researchers are now investigating the effects of continuing the program for a full year. Gender, race, socioeconomic factors or parental education did not change the impact of the exercise program.

The effects are consistent with other studies involving older adults. It should be emphasized that these were sedentary, overweight children. These findings are telling us what the lack of exercise is doing to young minds. I note the report just previous, about counteracting what we have regarded as “normal” brain atrophy in older adults by the simple action of walking for 40 minutes three times a week. Children and older adults might be regarded as our canaries in the coal mine, more vulnerable to many factors that can affect the brain. We should take heed.

Another study has come out proclaiming the cognitive benefits of walking for older adults. Previously sedentary adults aged 55-80 who walked around a track for 40 minutes on three days a week for a year increased the size of their hippocampus, as well as their level of BDNF. Those assigned to a stretching routine showed no such growth. There were 120 participants in the study.

The growth of around 2% contrasts with the average loss of 1.4% hippocampal tissue in the stretching group — an amount of atrophy considered “normal” with age. Although both groups improved their performance on a computerized spatial memory test, the walkers improved more.

The findings are consistent with a number of animal studies showing aerobic exercise increases neurogenesis and BDNF in the hippocampus, and human studies pointing to a lower risk of cognitive decline and dementia in those who walk regularly.

A study involving 68 healthy older adults (65-85) has compared brain activity among four groups, determined whether or not they carry the Alzheimer’s gene ApoE4 and whether their physical activity is reported to be high or low. The participants performed a task involving the discrimination of famous people, which engages 15 different functional regions of the brain. Among those carrying the gene, those with higher physical activity showed greater activation in many regions than those who were sedentary. Moreover, physically active people with the gene had greater brain activity than physically active people without the gene.

And adding to the evidence supporting the potential for exercise to lower the risk of dementia, another recent study has found that after ten years exercise (in terms of the number of different types of exercises performed and number of exercise sessions lasting at least 20 minutes) was inversely associated with the onset of cognitive impairment. The study used data from the National Long Term Care Survey.

More evidence that vascular disease plays a crucial role in age-related cognitive impairment and Alzheimer’s comes from data from participants in the Alzheimer's Disease Neuroimaging Initiative.

The study involved more than 800 older adults (55-90), including around 200 cognitively normal individuals, around 400 people with mild cognitive impairment, and 200 people with Alzheimer's disease. The first two groups were followed for 3 years, and the Alzheimer’s patients for two. The study found that the extent of white matter hyperintensities (areas of damaged brain tissue typically caused by cardiovascular disease) was an important predictor of cognitive decline.

Participants whose white matter hyperintensities were significantly above average at the beginning of the study lost more points each year in cognitive testing than those whose white matter hyperintensities were average at baseline. Those with mild cognitive impairment or Alzheimer's disease at baseline had additional declines on their cognitive testing each year, meaning that the presence of white matter hyperintensities and MCI or Alzheimer's disease together added up to even faster and steeper cognitive decline.

The crucial point is that this was happening in the absence of major cardiovascular events such as heart attacks, indicating that it’s not enough to just reduce your cardiovascular risk factors to a moderate level — every little bit of vascular damage counts.

A long-running study involving 299 older adults (average age 78) has found that those who walked at least 72 blocks during a week of recorded activity (around six to nine miles) had greater gray matter volume nine years later. Gray matter does shrink as we get older, so this is not about growth so much as counteracting decline. Walking more than 72 blocks didn’t appear to confer any additional benefit (in terms of gray matter volume). Moreover, when assessed four years after that, those who had shown this increased brain size were only half as likely to have developed dementia (40% of the participants had developed dementia by this point).

Previous research has indicated that obesity in middle-age is linked to higher risk of cognitive decline and dementia in old age. Now a study of 32 middle-aged adults (40-60) has revealed that although obese, overweight and normal-weight participants all performed equally well on a difficult cognitive task (a working memory task called the 2-Back task), obese individuals displayed significantly lower activation in the right inferior parietal cortex. They also had lower insulin sensitivity than their normal weight and overweight peers (poor insulin sensitivity may ultimately lead to diabetes). Analysis pointed to the impaired insulin sensitivity mediating the relationship between task-related activation in that region and BMI.

This suggests that it is insulin sensitivity that is responsible for the higher risk of cognitive impairment later in life. The good news is that insulin sensitivity is able to be modified through exercise and diet.

A follow-up study to determine if a 12-week exercise intervention can reverse the differences is planned.

Brain imaging of 49 children aged 9-10 has found that those who were physically fit had a hippocampus significantly bigger (around 12%) than those who were not fit. Animal studies and those with older adults have shown that aerobic exercise increases the growth of new brain cells in the hippocampus. Physical fitness was measured by how efficiently the children used oxygen while running on a treadmill. Fitter children also did better on tests of relational (but not item) memory, and this association was directly mediated by hippocampal volume.

A small study comparing 18 obese adolescents with type 2 diabetes and equally obese adolescents without diabetes or pre-diabetes has found that those with diabetes had significantly impaired cognitive performance, as well as clear abnormalities in the integrity of their white matter (specifically, reduced white matter volume, especially in the frontal lobe, as well as impaired integrity in both white and grey matter). Similar abnormalities have previously been found in adults with type 2 diabetes, but the subjects were elderly and, after many years of diabetes, generally had significant vascular disease. One study involving middle-aged diabetics found a reduction in the volume of the hippocampus, which was directly associated with poor glycaemic control.

It remains to be seen whether such changes can be reversed by exercise and diet interventions. While those with diabetes performed worse in all cognitive tasks tested, the differences were only significant for intellectual functioning, verbal memory and psychomotor efficiency.

I have often spoken of the mantra: What’s good for your heart is good for your brain. The links between cardiovascular risk factors and cognitive decline gets more confirmation in this latest finding that people whose hearts pumped less blood had smaller brains than those whose hearts pumped more blood. The study involved 1,504 participants of the decades-long Framingham Offspring Cohort who did not have a history of stroke, transient ischemic attack or dementia. Participants were 34 to 84 years old.

Worryingly, it wasn’t simply those with the least amount of blood pumping from the heart who had significantly more brain atrophy (equivalent to almost two years more brain aging) than the people with the highest cardiac index. Those with levels at the bottom end of normal showed similar levels of brain atrophy. Moreover, although only 7% of the participants had heart disease, 30% had a low cardiac index.

On the subject of the benefits of walking for seniors, it’s intriguing to note a recent pilot study that found frail seniors who walked slowly (no faster than one meter per second) benefited from a brain fitness program known as Mindfit. After eight weeks of sessions three times weekly (each session 45-60 minutes), all ten participants walked a little faster, and significantly faster while talking. Walking while talking requires considerably more concentration than normal walking. The success of this short intervention (which needs to be replicated in a larger study) offers the hope that frail elderly who may be unable to participate in physical exercise, could improve their mobility through brain fitness programs. Poor gait speed is also correlated with a higher probability of falls.

The connection between gait speed and cognitive function is an interesting one. Previous research has indicated that slow gait should alert doctors to check for cognitive impairment. One study found severe white matter lesions were more likely in those with gait and balance problems. Most recently, a longitudinal study involving over 900 older adults has found poorer global cognitive function, verbal memory, and executive function, were all predictive of greater decline in gait speed.

A study involving 65 older adults (59-80), who were very sedentary before the study (reporting less than two episodes of physical activity lasting 30 minutes or more in the previous six months), has found that those who joined a walking group improved their cognitive performance and the connectivity in important brain circuits after a year. However, those who joined a stretching and toning group showed no such improvement. The walking program involved three 40-minute walks at a moderate pace every week. The two affected brain circuits (the default mode network and the fronto-executive network) typically become less connected with age. It is worth emphasizing that the improvement was not evident at the first test, after six months, but only at the second 12-month test.

Interestingly, I noticed in the same journal issue a study into the long-term benefits of dancing for older adults. The study compared physical and cognitive performance of those who had engaged in amateur dancing for many years (average: 16.5 years) and those with no dancing or sporting engagement. The dancing group were overall significantly better than the other group on all tests: posture, balance, reaction time, motor behavior, cognitive performance. However, the best dancers weren’t any better than individuals in the other group; the group difference arose because none of the dancers performed poorly, while many of the other group did.

A German study involving nearly 4000 older adults (55+) has found that physical activity significantly reduced the risk of developing mild cognitive impairment over a two-year period. Nearly 14% of those with no physical activity at the start of the study developed cognitive impairment, compared to 6.7% of those with moderate activity, and 5.1% of those with high activity. Moderate activity was defined as less than 3 times a week.

In another report, a study involving 1,324 individuals without dementia found those who reported performing moderate exercise during midlife or late life were significantly less likely to have MCI. Midlife moderate exercise was associated with 39% reduction in the odds of developing MCI, and moderate exercise in late life was associated with a 32% reduction. Light exercise (such as bowling, slow dancing or golfing with a cart) or vigorous exercise (including jogging, skiing and racquetball) were not significantly associated with reduced risk for MCI.

And in a clinical trial involving 33 older adults (55-85) with MCI has found that women who exercised at high intensity levels with an aerobics trainer for 45 to 60 minutes per day, four days per week, significantly improved performance on multiple tests of executive function, compared to those who engaged in low-intensity stretching exercises. The results for men were less significant: high-intensity aerobics was associated only with improved performance on one cognitive task, Trail-making test B, a test of visual attention and task-switching.

A study involving 155 women aged 65-75 has found that those who participated in resistance training once or twice weekly for a year significantly improved their selective attention (maintaining mental focus) and conflict resolution (as well as muscular function of course!), compared to those who participated in twice-weekly balance and tone training. Performance on the Stroop test improved by 12.6% and 10.9% in the once-weekly and twice-weekly resistance training groups respectively, while it deteriorated by 0.5% in the balance and tone group. Improved attention and conflict resolution was also significantly associated with increased gait speed.

A large longitudinal study, comparing physical activity at teenage, age 30, age 50, and late life against cognition of 9,344 women, has revealed that women who are physically active at any point have a lower risk of cognitive impairment in late-life compared to those who are inactive, but teenage physical activity is the most important. When age, education, marital status, diabetes, hypertension, depressive symptoms, smoking, and BMI were accounted for, only teenage physical activity status remained significantly associated with cognitive performance in old age. Although becoming active later in life didn’t make up for being inactive in adolescence, it did significantly reduce the risk of cognitive impairment compared to those who remained physically inactive. The findings are a strong argument for greater effort in increasing physical activity in today's youth.

A theory that changes in fat metabolism in the membranes of nerve cells play a role in Alzheimer's has been supported in a recent study. The study found significantly higher levels of ceramide and cholesterol in the middle frontal gyrus of Alzheimer's patients. The researchers suggest that alterations in fats (especially cholesterol and ceramide) may contribute to a "neurodegenerative cascade" that destroys neurons in Alzheimer's, and that the accumulation of ceramide and cholesterol is triggered by the oxidative stress brought on by the presence of the toxic beta amyloid peptide. The study also suggests a reason for why antioxidants such as vitamin E might delay the onset of Alzheimer's: treatment with Vitamin E reduced the levels of ceramide and cholesterol, resulting in "a significant decrease in the number of neurons killed by the beta amyloid and oxidative stress.

Older news items (pre-2010) brought over from the old website

Exercise can aid recovery after brain radiation

A mouse study has found that exercise can prevent a decline in memory after whole-brain radiation treatment. Mice that had radiation plus access to a running wheel did as well at remembering where an escape hole in maze was as normal mice that didn't exercise. Irradiated mice that had no access to an exercise wheel eventually showed no particular preference for the section of the maze with the escape hole. The irradiated mice who didn’t exercise also showed depressive-like behavior, while those who exercised did not.

Older adults

A 7-year study of over 3000 seniors (70-79) using self-report physical activity (walking) found that 21% were consistently sedentary, 12% maintained their activity levels, 26% had declining levels, and 41% had increasing or fluctuating levels. After adjustment for age, sex, race, education, study site, diabetes, hypertension, smoking, alcohol consumption and baseline cognitive score, they found that those who were sedentary throughout the study had the lowest levels of cognitive function at the beginning and experienced the fastest rate of cognitive decline; cognitive decline also was faster in those whose physical activity levels consistently declined during the study period. However, sedentary elders who increased their physical activity improved their cognitive function, especially the ability to process complex information quickly.

Barnes, D.E. et al. 2009. The impact of changes in physical activity levels on rate of cognitive decline in a biracial cohort of non-demented elders. Presented at the Alzheimer's Association International Conference on Alzheimer's Disease July 11-16 in Vienna.

A study of 90 post-menopausal women found that long-term strenuous activity was consistently associated with poorer performance on all eight cognitive tests, in particular tests of semantic memory, working memory, delayed verbal recall, and sustained attention. However, moderate physical activity was consistently associated with better performance on all eight of the tests, especially cognitive flexibility, working memory, and sustained attention.

Tierney, M.C. et al. 2009. Intensity of long-term physical activity and later life cognition in postmenopausal women. Presented at the Alzheimer's Association International Conference on Alzheimer's Disease July 11-16 in Vienna.

A study of some 1800 seniors (60+) found that the association of physical activity with better cognitive function was significant only for those who didn’t carry any copies of the “Alzheimer’s gene” APOE-e4 (which is the majority of people), and was greater with age.

Physical fitness improves memory in seniors

A study of 165 older adults (59-81) has found a significant association between physical fitness and performance on certain spatial memory tests. Fitness was also strongly correlated with hippocampus size. Although rodent studies have shown that exercise increases hippocampus size and spatial memory, this is the first study to show that in humans. The findings provide more evidence for the benefits of physical exercise in preventing memory loss in older adults.

Exercise prevents stem cell drop in middle age

Following mouse research showing that the creation of new brain cells (neurogenesis) in the dentate gyrus drops off dramatically by the time mice are middle aged and that exercise can significantly slow that trend, a new mouse study has confirmed these findings and found evidence that exercise has this effect by increasing the production of BDNF.

Age differences in cognitive benefits of exercise and mental stimulation

A mouse study has found that while physical exercise (a running wheel) and mental stimulation (toys), singly and together, improved memory in old mice, exercise alone or exercise and stimulation improved memory in middle-aged mice but not stimulation alone, and only exercise alone benefited young mice. The results suggest that as we get old and maybe less able to exercise, cognitive stimulation can help to compensate, but exercise is central to memory reinforcement at all ages.

Fitness and childhood IQ indicators of cognitive ability in old age

Data from the Scottish Mental Survey of 1932 has revealed that physical fitness contributed more than 3% of the differences in cognitive ability in old age. The study involved 460 men and women, who were tested using the same cognitive test at age 79 that they had undergone at age 11. Physical fitness was defined by time to walk six meters, grip strength and lung function. Childhood IQ was also significantly related to lung function at age 79, perhaps because people with higher intelligence might respond more favorably to health messages about staying fit. But physical fitness was more important for cognitive ability in old age than childhood IQ. People in more professional occupations and with more education also had better fitness and higher cognitive test scores at 79.

Exercise helps sustain mental activity as we age

A review of the research on the effects of exercise on brain functioning supports the view that physical exercise helps people maintain cognitive abilities well into older age. There’s also evidence that fitness training may improve some mental processes even more than moderate activity. The review examined three types of study: epidemiological studies, human intervention studies, and animal studies. All provide support for the benefits of physical activity for the aging brain.

Kramer, A.F., Colcombe, S.J., Erickson, K. & Scalf, P. 2006. Fitness Training and the Brain: From Molecules to Minds. Presented August 11 at the 114th Annual Convention of the American Psychological Association (APA).

A review of 96 papers involving 36 very large, ongoing epidemiological studies in North America and Europe looking at factors involved in maintaining cognitive and emotional health in adults as they age has concluded that controlling cardiovascular risk factors, such as reducing blood pressure, reducing weight, reducing cholesterol, treating (or preferably avoiding) diabetes, and not smoking, is important for maintaining brain health as we age. The link between hypertension and cognitive decline was the most robust across studies. They also found a consistent close correlation between physical activity and brain health. However, they caution that more research is needed before specific recommendations can be made about which types of exercise and how much exercise are beneficial. They also found protective factors most consistently reported for cognitive health included higher education level, higher socio-economic status, emotional support, better initial performance on cognitive tests, better lung capacity, more physical exercise, moderate alcohol use, and use of vitamin supplements. Psychosocial factors, such as social disengagement and depressed mood, are associated with both poorer cognitive and emotional health in late life. Increased mental activity throughout life, such as learning new things, may also benefit brain health.

A study of 54 postmenopausal women (aged 58 to 80) suggests that being physically fit offsets cognitive declines attributed to long-term hormone-replacement therapy. It was found that gray matter in four regions (left and right prefrontal cortex, left parahippocampal gyrus and left subgenual cortex) was progressively reduced with longer hormone treatment, with the decline beginning after more than 10 years of treatment. Therapy shorter than 10 years was associated with increased tissue volume. Higher fitness scores were also associated with greater tissue volume. Those undergoing long-term hormone therapy had more modest declines in tissue loss if their fitness level was high. Higher fitness levels were also associated with greater prefrontal white matter regions and in the genu of the corpus callosum. The findings need to be replicated with a larger sample, but are in line with animal studies finding that estrogen and exercise have similar effects: both stimulate brain-derived neurotrophic factor.

Lifestyle changes improve seniors’ memory surprisingly quickly

A small 14-day study found that those following a memory improvement plan that included memory training, a healthy diet, physical exercise, and stress reduction, showed a 5% decrease in brain metabolism in the dorsal lateral prefrontal region of the brain (involved in working memory) suggesting they were using their brain more efficiently. This change in activity was reflected in better performance on a cognitive measure controlled by this brain region, and participants reported that they felt their memory had improved. The memory training involved doing brainteasers, crossword puzzles and memory exercises. Diet involved eating 5 small meals daily (to prevent fluctuations in blood glucose levels) that were rich in omega-3 fats, low-glycemic index carbohydrates (e.g., whole grains) and antioxidants. Physical exercise involved brisk walking and stretching, and stress reduction involved stretching and relaxation exercises.

The study was presented at the American College of Neuropsychopharmacology's Annual Meeting on December 11-15, in Hawaii.

Lifelong mild exercise decreases cellular aging in the brain

A rat study has provided evidence that regular, light exercise (say a daily 30-minute walk or a light 1-mile run) decreases cellular aging in the brain. Those rats who had had access to an exercise wheel during their lives showed fewer byproducts of oxidative stress in their brains, and their DNA at two years resembled that of their 6 month old counterparts.

The research was presented at the Society for Neuroscience's 35th annual meeting in Washington, D.C.

Diet, exercise, stimulating environment helps old dogs learn

A new study of beagles provides more evidence that diet and mental stimulation are important in reducing or preventing age-related cognitive decline. The study, involving 48 older beagles (aged 7 to 11), compared four combinations of behavioral enrichment (regular exercise and lots of mental stimulation) and supplementation of diet with antioxidants had on a beagle's ability to learn: regular diet and regular experience; regular diet and enriched experience; regular experience and an enriched diet; and enriched diet and an enriched experience. The study followed the beagles over two years. Those in the groups with either an enriched diet or enriched environment did better than those without either, but those who had both the enriched diet and an enriched environment did noticeably better than all the rest.

Maintaining physical activity linked to less cognitive decline in older men

Longer and more intense physical activity may help people maintain their cognitive skills as they age, according to a 10-year study of 295 men, born between 1900 and 1920, from the Finland, Italy and Netherlands Elderly (FINE) Study. The study showed that over 10 years the cognitive decline in men who had reduced their daily physical activity by an hour or more was 2.6 times greater than the decline in men who maintained their activity. Men who performed their daily physical activity with a lower intensity 10 years later had a 3.6 times stronger decline than men who maintained the intensity level. Men who engaged in activities of the lowest intensity had up to 3.5 times greater decline than men who participated in activities with a higher intensity. There was no decline among those who increased the duration or intensity of their activities. Activities of medium-to-low intensity, such as walking three miles per day, was associated with less cognitive decline than the lowest-intensity activity like walking less than three miles per day.

Walking may protect elderly from dementia

A study of more than 2,200 Japanese-American men between the ages of 71 and 93 has found that elderly men who are sedentary or walk less than a quarter of a mile per day are nearly twice as likely to develop dementia and Alzheimer's disease compared to men who walk more than two miles per day. Those who walked less than a mile (and more than quarter of a mile) a day also showed a significantly greater risk of dementia than those walking more than two miles a day.

Since 1986, 18,766 women, aged 70 to 81 years, have been questioned on their physical activity in biennial questionnaires. The women were divided into five groups depending on their average energy expenditures. Those in the highest activity grouping had a 20% lower risk of cognitive impairment than women in the lowest. Women who walked at an easy pace for at least 1.5 hours per week had higher cognitive scores than those who walked less than forty minutes per week.

Music with exercise boosts mental performance

In the first study to look at the combined effects of music and short-term exercise on mental performance, researchers found that listening to music while exercising helped to increase scores on a verbal fluency test among cardiac rehabilitation patients. The study included 33 men and women in the final weeks of a cardiac rehabilitation program. Participants completed a verbal fluency test before and after two separate sessions of exercising on a treadmill. The workouts were scheduled a week apart and lasted about 30 minutes. Participants listened to classical music – Vivaldi's "The Four Seasons" – during one of the sessions. Participants reported feeling better emotionally and mentally after working out regardless of whether or not they listened to music. But the improvement in verbal fluency test performance after listening to music was more than double that of the non-music condition.

Exercise improves attention and decision-making among seniors

An imaging study involving adults ranging in age from 58 to 78 before and after a six-month program of aerobic exercise, found specific functional differences in the middle-frontal and superior parietal regions of the brain that changed with improved aerobic fitness. Consistent with the functions of these brain regions, those who participated in the aerobic-exercise intervention significantly improved their performance on a computer-based decision-making task. Those doing toning and stretching exercises did increase activation in some areas of the brain but not in those tied to better performance. Their performance on the task was not significantly different after the exercise program. The aerobic exercise used in the study involved gradually increasing periods of walking over three months. For the final three months of the intervention program, each subject walked briskly for 45 minutes in three sessions each week.

High sugar blood levels linked to poor memory

A new study takes an important step in explaining cognitive impairment in diabetics, and suggests a possible cause for some age-related memory impairment. The study assessed non-diabetic middle-aged and elderly people. Those with impaired glucose tolerance (a pre-diabetic condition) had a smaller hippocampus and scored worse on tests for recent memory. These results were independent of age or overall cognitive performance. The brain uses glucose almost exclusively as a fuel source. The ability to get glucose from the blood is reduced in diabetes. The study raises the possibility that exercise and weight loss, which help control blood sugar levels, may be able to reverse some of the memory loss that accompanies aging.

Imaging study confirms link between exercise and cognitive function

A number of studies have suggested a link between exercise and cognitive function in older adults, but now an imaging study shows that there are actual anatomical differences in the brains of physically fit versus less fit older adults (over 55). Specifically, they found very distinct differences in the gray and white matter in the frontal, temporal, and parietal cortexes. With aging, these tissues shrink, a reduction closely matched by declines in cognitive performance. Fitness, it appears, slows that decline. A related study, published in March, suggests that women may benefit more from exercise than men.

Walking reduces cognitive decline in older women

A study that tested the cognitive abilities of 5,925 women who were 65 and older once and then again six to eight years later, found that the women who walked the least were most likely to develop cognitive decline -- 24 percent of them had significant declines in their test scores, compared to 17 percent of the most active group. The least active women walked an average of about a half mile per week, while the most active group walked an average of nearly 18 miles per week.While any exercise appeared to be helpful, the benefit increased with every extra mile walked per week. Examples of activities that would reduce the risk of cognitive decline were: playing tennis twice a week, walking a mile per day, playing golf once a week.

The paper was presented by Kristine Yaffe at the American Academy of Neurology’s 53rd Annual Meeting in Philadelphia, May 5-11.

Aerobic exercise improves some mental processes in older adults

The team of Duke University Medical Center researchers who demonstrated in late 1999 that aerobic exercise is just as effective as medication in treating major depression in the middle-aged and elderly has now reported that the same exercise program also appears to improve the cognitive abilities of these patients. The researchers found significant improvements in the higher mental processes of memory and the so-called executive functions, which include planning, organization and the ability to mentally juggle different intellectual tasks at the same time. Attention and concentration did not appear to be affected. Because it has been theorised that a reduction in blood flow to the brain might be one of the reasons why the elderly – especially those with coronary artery disease or hypertension – might suffer some degree of cognitive decline, it is speculated that exercise might improve cognitive functioning in such patients by improving the flow of oxygen-rich blood to specific regions of the brain.

124 previously sedentary adults, 60 to 75 years old, were randomly assigned to either aerobic (walking) or anaerobic (stretching and toning) exercise over a period of 6 months. Those who received aerobic training showed substantial improvements in performance on tasks requiring executive control (such as planning, scheduling, inhibition and working memory) compared with anaerobically trained subjects. Executive control processes are particularly affected by aging. The walking condition involved walking rapidly for 45 minutes three days a week.

The benefits of physical exercise for cognitive and memory performance in the elderly have not been consistently demonstrated in research. This study, a longitudinal one (the Interdisciplinary Ageing (IDA) study), was designed to reduce perceived shortcomings of earlier research.

The 442 people ( 65 - 95 years old) involved in the study had had their medical data collected regularly since 1965. 46 volunteers from this group (18 women and 28 men; mean age73.2 years) participated in an eight-week resistance training program. The program involved a warm-up lasting 10 min, followed by eight resistance exercises on machines.

PParticipants displayed a significant increase in muscular strength directly after the training, and this was still significant one year later. However, there was no improvement in any subjective health ratings or psychological well-being measures, with the exception of a decrease inself-attentiveness (fewer self-centred thoughts; less anxiety about themselves and the future).

There was however a positive effect on cognitive function. Memory recall and recognition were both improved, and was still significant a year later. It is unlikely that this long-term improvement can be directly due to such a short-term physical training program, but perhaps the experience of mastering a new situation and changing established habits increased participants' motivation to seek new challenges. This openness and self-confidence could be responsible for participants staying physically, socially and mentally active and being self-reliant, all of which are prerequisites for optimal cognitive functioning.

Perrig-Chiello, P. 1998. The effects of resistance training on well-being and memory in elderly volunteers. Age and Ageing, 27

Physical activity reduces MCI

A German study involving nearly 4000 older adults (55+) has found that physical activity significantly reduced the risk of developing mild cognitive impairment over a two-year period. Nearly 14% of those with no physical activity at the start of the study developed cognitive impairment, compared to 6.7% of those with moderate activity, and 5.1% of those with high activity. Moderate activity was defined as less than 3 times a week.

Exercise and Mediterranean-type diet associated with lower risk for Alzheimer's

A New York study involving 1880 elderly (average age 77) is the first to investigate both exercise and diet in connection with the later development of Alzheimer’s (within a five and a half year period). Participants were asked about their activity in the two weeks prior to the interview, about the regularity and duration, as well as the quality (vigorous, moderate, light). They were also asked about their food consumption over the previous year, and their responses grouped into nine food categories, the sum of which represented a Mediterranean-type diet score. Those who were very physically active had a 33% risk reduction of Alzheimer's; those who adhered more strongly to a Mediterranean-type diet had a 40% risk reduction. Those who did both had a 60% reduction. A Mediterranean-type diet is typically characterized by high intake of fish, vegetables, legumes, fruits, cereals and monounsaturated fatty acids; relatively low intake of dairy products, meats and saturated fats; and moderate alcohol consumption.

Moderate exercise helps mild cognitive impairment

An Australian study involving 138 older adults (50 years and over) with mild cognitive impairment, has found that those who undertook to achieve 2 ½ hours of physical activity each week (three 50 minute sessions), ranging from walking, ballroom dancing to swimming, for a six month period, continually out-scored the control group on cognitive tests during the 18 month testing period — showing that memory improvement was still evident a year after the supervised exercise period.

Exercise may slow brain shrinkage in early Alzheimer's

A study of 121 people age 60 and older, of whom 57 were in the early stages of Alzheimer's disease, has found that those with early Alzheimer's disease who were less physically fit (measured by cardiorespiratory fitness) had four times more brain shrinkage when compared to normal older adults than those who were more physically fit. The findings suggest the value of physical fitness in slowing down the progression of Alzheimer's disease. The association existed even after age, gender, severity of dementia, physical activity and frailty were accounted for. There was no relationship between higher fitness levels and brain changes in the group of people without dementia.

Mental and physical exercise delays dementia

A study using genetically engineered mice has found providing the mice with an enriched environment that enhanced their mental and physical stimulation improved performance on memory tests at an early stage of Huntington's disease, when memory impairment has begun. Specific molecular changes were also observed at the synapses in the hippocampus. Those without increased mental and physical activity showed decreased levels of specific proteins that are expressed at the synapse, but those exposed to stimulation didn’t. The finding offers hope for slowing the progression of the disease, as well as other dementias.

A four-year study involving 749 older adults has found that the top one-third of participants who exerted the most energy in moderate activities such as walking were significantly less likely to develop vascular dementia than those people in the bottom one-third of the group. Contrary to some reports, no such association was found with Alzheimer’s disease.

How mental and physical stimulation slows Alzheimer's

A new study reveals how mental and physical activity slows the cognitive decline seen in Alzheimer’s. In the study, genetically engineered mice were housed in either standard cages or ones with access to an enriched environment. After five months, the mice housed in the enriched environment had fewer Ab plaques, smaller plaque size, and reduced amyloid angiopathy compared to mice housed in standard cages. However there were no differences in the levels of soluble Ab peptide or the expression levels of its precursor protein (APP). Further investigation revealed differences suggesting that an enriched environment elicits protection via pathways that prevent Ab accumulation and enhance its clearance. The data confirm that an environment rich in mental and physical stimulation slows the progression of Alzheimer-like brain pathology.

Good physical function linked to Alzheimer's delay

A study following 2,288 older adults for six years found that those whose physical function was higher at the start of the study were three times less likely to develop dementia than were those whose physical function was lower.

Exercise protects against Alzheimer's

A study following 1,740 seniors (aged 65 and older) over a six-year period, found that those who exercised three or more times a week had a 30 — 40% lower risk for developing dementia compared with those who exercised fewer than three times per week. Even modest amounts, such as walking 15 minutes a day, appear beneficial, and the more frail the person was, the more they benefited from regular exercise.

Exercise slows development of Alzheimer's-like brain changes in mice

Population-based studies have provided evidence that various lifestyle interventions might help slow the onset and progression of Alzheimer’s. A mouse study now provides a clue how that might work. Physical activity enhanced the learning ability of mice genetically engineered to develop amyloid plaques and decreased the level of plaque-forming beta-amyloid protein fragments in their brains. The mice were divided into mice with access to running wheels or no access. The findings are supported by another recent study that found that beta-amyloid levels decreased in the brains of another kind of transgenic mice when they were housed in groups and in environments that were enriched with running wheels, colored tunnels, and toys.

Enriched environment delays onset of Alzheimer's in mice

A study of genetically engineered mice has found that an enriched environment, with more opportunities to exercise, explore and interact with others, can dramatically reduce levels of beta-amyloid peptides, hallmarks of Alzheimer's disease. The mice also showed greater activity for several genes involved in memory and learning, the growth of new nerve cells, cell survival, and the growth of new blood vessels within the brain. As with humans, mice in the enriched environment showed varying levels of activity. The most active were found to have the least beta-amyloid. Researchers suggested the reason may simply be a matter of blood flow; physical and mental activity can stimulate growth of new blood vessels and keep existing vessels open and functional.

Why diet, hormones, exercise might delay Alzheimer’s

A theory that changes in fat metabolism in the membranes of nerve cells play a role in Alzheimer's has been supported in a recent study. The study found significantly higher levels of ceramide and cholesterol in the middle frontal gyrus of Alzheimer's patients. The researchers suggest that alterations in fats (especially cholesterol and ceramide) may contribute to a "neurodegenerative cascade" that destroys neurons in Alzheimer's, and that the accumulation of ceramide and cholesterol is triggered by the oxidative stress brought on by the presence of the toxic beta amyloid peptide. The study also suggests a reason for why antioxidants such as vitamin E might delay the onset of Alzheimer's: treatment with Vitamin E reduced the levels of ceramide and cholesterol, resulting in "a significant decrease in the number of neurons killed by the beta amyloid and oxidative stress.

Children & young adults

Aerobic fitness boosts IQ in teenage boys

Data from the 1.2 million Swedish men born between 1950 and 1976 who enlisted for mandatory military service at the age of 18 has revealed that on every measure of cognitive performance, average test scores increased according to aerobic fitness — but not muscle strength. The link was strongest for logical thinking and verbal comprehension, and the association was restricted to cardiovascular fitness. The results of the study also underline the importance of getting healthier between the ages of 15 and 18 while the brain is still changing — those who improved their cardiovascular health between 15 and 18 showed significantly greater intelligence scores than those who became less healthy over the same time period. Those who were fittest at 18 were also more likely to go to college. Although association doesn’t prove cause, the fact that the association was only with cardiovascular fitness and not strength supports a cardiovascular effect on brain function. Results from over 260,000 full-sibling pairs, over 3,000 sets of twins, and more than 1,400 sets of identical twins, also supports a causal relationship.

Vigorous exercise helps children's grades

214 sixth graders were divided into two groups — one group took a general physical education class in the first semester, then a non-physical education course in the next semester. The other group did the classes in the other order. There was no difference in performance in academic classes between those taking the physical education course and those taking the non-physical. However, students who took part in more vigorous physical activities at least three times a week (such as soccer, skateboarding) did better in academic subjects (by around 10%). It’s worth noting that PE classes only averaged 19 minutes of moderate or vigorous activity; activity outside the classroom was assessed in 30 minute blocks. Only vigorous activity impacted academic performance.

Physically fit children appear to do better in classroom

Several studies in recent years have demonstrated that exercise may improve cognitive functioning in older adults. New research suggests the same may be true of children. Preliminary results from a series of studies over the past two years have found a strong relationship between academic achievement and fitness scores. One of these studies also found that fit children were faster and more accurate at a visual discrimination task than sedentary children.

The study was presented at the annual meeting of the Society for Psychophysiological Research in Santa Fe, N.M., Oct. 20-24.

Lack of benefit

A study of 90 post-menopausal women found that long-term strenuous activity was consistently associated with poorer performance on all eight cognitive tests, in particular tests of semantic memory, working memory, delayed verbal recall, and sustained attention. However, moderate physical activity was consistently associated with better performance on all eight of the tests, especially cognitive flexibility, working memory, and sustained attention.

Tierney, M.C. et al. 2009. Intensity of long-term physical activity and later life cognition in postmenopausal women. Presented at the Alzheimer's Association International Conference on Alzheimer's Disease July 11-16 in Vienna.

A study of some 1800 seniors (60+) found that the association of physical activity with better cognitive function was significant only for those who didn’t carry any copies of the “Alzheimer’s gene” APOE-e4 (which is the majority of people), and was greater with age.

Some people are 'immune' to exercise

In view of the apparent benefits of exercise for cognitive function suggested by recent research, it is worth noting that a study involving 742 people from 213 families has found that "There is astounding variation in the response to exercise. The vast majority will benefit in some way, but there will be a minority who will not benefit at all."

The results were reported at the Australian Health and Medical Research Congress in Sydney, Australia.